Chess Thought Process
For several months from spring 2008 I became, overnight, obsessed with chess. This lasted until the following January, during which period I played and studied the game obsessively.
I haven't played for many years since, but I recently found some old files and post the following just in case it might prove useful to someone.
Good chess is mostly dependent on pattern recognition, a skill that's best developed through years of practice. For what my advice is worth (I didn't stick with it long enough to get very good), I'd recommend those just starting out spend the vast bulk of their time studying tactical motifs. These days that's best done on an adaptive chess server, such as Chess Tempo. You can read books about strategy and tactics, go through master games and all the rest later on.
But one thing to get right straight away is ingraining the correct thought process until it is second nature; you need a systematic and thorough approach to the way you think about the game. My approach is below, firstly in summary form and then in full, which is itself a summary of the ideas of NM Dan Heisman and his concept of Real Chess.
See the links referenced below for much more detail.
Real Chess Thought Process: Checklist
1) Static evaluation (material, safety, activity, pawn structure)
2) ALL changes in the position caused by opponent's last move (incl. guard changes, discoveries, etc.)
3) ALL threats caused by opponent's last move (incl. discovered threats)
4a) ALL checks, captures and threats I could make on my move (each counts as a candidate move)
4b) ALL checks, captures and threats opponent could make in response, I could make in counter-response, etc.
4c) Continue for each half-move until position reaches quiescence
5) Dynamic evaluation of final position resulting from each candidate move to determine which move to play
6) Final sanity check
Real Chess: Complete Thought Process
1) Static Evaluation: evaluate the position before beginning move analysis. The four main criteria for positional evaluation are: material; King safety; piece activity/mobility; and (to a lesser extent unless the other factors are equal) pawn structure. Who is better, by how much, and why? The imbalances in the static evaluation help to form your plan and act as a guide to help you decide which moves are reasonable candidates and which moves can be safely ruled out, and they also help you to determine your opponent's plan. A comprehensive static evaluation, along with the analysis of strategic considerations, can often be accomplished on your opponent's time; therefore on your present move you can just focus on how your opponent's last move changed the static evaluation, by how much and why.
2) Consider tactical changes in the position caused by your opponent's last move. Why was that move played? How did your opponent's move meet any threats you made last move? What is each piece doing (guarding, pinning, attacking, blocking, etc.)? What can either player do now that you could not do before (there could be multiple things!), and equally importantly what can either of you not do now that you could do before (including whether the piece that moved is safe on that square, i.e. is there a sequence of captures on that square or the possibility of trapping the piece and thus winning material)? The changes to look for include in particular the counting of 'guard' changes, discovered threats, blocked lines and newly-weakened squares. Follow this process for each potential half-move in each line that you consider.
3) Consider ALL threats resulting from your opponent's last move, even if the move made was the one you were expecting and you have already analyzed it. Was there a check or capture? Is she threatening anything nasty? Any forcing sequences? Assume that one exists until you can prove that it doesn't. Determine your opponent's threats by imagining skipping your own move, giving your opponent a second move in a row (but not necessarily with the same piece, of course!). Threats do not necessarily only come from the piece that just moved; there could be indirect discovered threats as well. The biggest threats are mating threats. You can either stop your opponent's threat (the simplest choice), make a bigger counterthreat of your own, possibly a zwischenzug (though this generally complicates the position and is thus more prone to calculation errors and misjudgements), or ignore the threat if you have an overwhelming attack going. If your opponent did make a move such that your reply is forced, you no longer need to consider candidate moves that do not address this threat. If instead there was no check, capture or threat (i.e. your opponent made either a quiet positional move or possibly a tactical error) move on to step 4 below.
4) Consider ALL the checks, captures and threats you could make on your move, ALL the checks, captures and threats that your opponent could make in reply to each of your candidate moves and ALL the checks, captures and threats you could make in return (i.e. calculate all lines at least 3 ply deep or until quiescence – whichever is deepest), always starting with the most plausible responses at each level of the tree; breadth is much more important than depth, due to the relative likelihood of moves in a sequence decreasing greatly with increased depth in the tree. The process for determining your own threats on your candidate moves works similarly to the process for determining threats made by your opponent, as outlined above. Always assume your opponent will make the best possible reply to your move, and always work out what that best reply is. Note that even if your opponent is forced to make a particular move in response to a threat of yours, you still need to analyze this forced move to see if it contains any new threats of its own!
If there are no good checks, captures or threats look to improve the position: if there is no material to be won, the two criteria to concentrate on improving are the safety and activity of all your pieces relative to your opponent's pieces (pawn structure gets more important in the endgame, primarily because a bad pawn structure ties pieces down to defending the pawns that can't defend themselves, thus reducing these pieces' activity). This includes getting or keeping the initiative, increasing your own piece activity (which of your pieces is currently doing the least?) or reducing enemy piece activity (e.g. by blockading with a pawn or Knight), eliminating key enemy pieces by making favourable exchanges (e.g. exchanging your own bad pieces for your opponent's good ones or swapping off pieces when you have a lead in material), increasing pressure on pieces or key squares by attacking them, and improving your own King safety or opening up the position around the enemy King. Have a plan based on each side's threats, strengths & weaknesses and make moves that accomplish the goals of the plan.
5) If you see a good move, look for a better one. Keep looking until you have found the best move on the board and worked out what the principle variation (strongest move made each ply) is likely to be. It is essential to examine all candidate moves and play the strongest one, rather than playing the first move you find that seems good. Some candidate moves are not safe and can be immediately eliminated. The strongest move out of the remaining candidates is found by evaluating the final position of each possible sequence of moves after the continuation reaches quiescence (i.e. all strong threats have been resolved), as far as this is possible (this is called dynamic evaluation); if the position is unclear, you must rely on judgement to decide whether the continuation has a greater than even chance of being better than the best available alternative move. If it appears that it does then the unclear move should be played; this is a calculated risk that is necessary in order to improve your positional judgement skills over time.
If your prior static evaluation was correct, the best move you could make will leave you as good relative to your opponent as you were prior to your move (i.e. the best move preserves the evaluation). This is because the static evaluation includes the fact that it is your move; your goal is to find the move whose dynamic evaluation equals the static evaluation.
6) Before making your move, do a final sanity check. Close your eyes, take a deep breath, then take a fresh look at the board, imaging your move having been played. Have you overlooked something silly? Any pieces left en prise? Any 'killer moves' for your opponent? If so, re-evaluate. If not, make your move with confidence and press the clock!
Note: book moves and forced moves (e.g. being in check or the middle of a (genuinely!) forced sequence of captures) can be excluded from this Real Chess thought process. But otherwise, you must play Real Chess on every single move! It only takes one mistake to lose the game, thus wasting all the work you put in previously. This thought process must therefore become second nature if you are to become a strong chess player.
Furthermore, in timed games it is necessary to play the strongest move you see given the time constraints imposed by the clock. Good time management consists of making maximum use of all the available time, saving extra time to spend on difficult, complex and/or critical positions and therefore playing simpler positions more quickly. This necessarily places constraints on the thinking process. Thus, it is imperative to learn to play Real Chess under actual playing conditions.
Remember: you are only as good as your worst move!
References
Everyone's Second Chess Book, Dan Heisman
Novice Nook nos. 10, 12, 14, 27, 29, 33, 36, 45, 51, 55, 57, 59, 61, 67, 83 & 89