This is a great topic, with great advice given already.
My contribution will be-
1. Developing a plan (for attack and defense).
2. Understanding why a move was played, not just memorize them.
3. Timing and sequence of moves are important.
4. Identifying weak squares for both players.
This is a great topic, with great advice given already.
My contribution will be-
1. Developing a plan (for attack and defense).
2. Understanding why a move was played, not just memorize them.
3. Timing and sequence of moves are important.
4. Identifying weak squares for both players.
I like your format. Well done and thank you. Perhaps we can develop a top 10, top 20, top 100 list.
1. Developing a plan (for attack and defense).
2. Understanding why a move was played, not just memorize them.
3. Timing and sequence of moves are important.
4. Identifying weak squares for both players.
5. Check for checks, captures and threats.
6. Develop knights before bishops.
7. Move each piece only once in the opening.
For 6. and 7., it would not be an "always" rule, but an "in general" rule - to guide the beginning chess player.
My apologies for not checking back on my own topic.
I do believe this topic will be of value for the beginning chess player, myself included, so I will continue. 
The Use of Space In Chess
Points to keep in mind regarding space.
1. Control the center prior to initiating attacks on the wing.
2. Avoid locking your bishops behind your own pawns.
3. If you have less space, try to exchange pieces of equal value.
4. If your opponent launches a flank attack, strike back in the center.
5. Keep the king away from the center until the endgame.
As a beginner id say the biggest things that have helped me become decent beginner are...
-understanding basic pawn structures. Lost so many games all because poor pawn play very early
-developing K and B and learning basic ways of using them for support.
-holding the middle
DONT QUIT. Play it out and who knows what happens vs beginners. Learn endgame stuff
For beginners, I would suggest FORGET about openings. They are a waste of time for you at first. You don't start out learning math by taking calculus, or to play piano by tackling Chopin concertos. You need to learn the basics well before proceeding to the more complex areas of the game.
To wit, the rules in post #9 are a good start, but I would add:
Develop Knights before Bishops - as a short range piece, they need to advance early - and Bishops before your Queen and Rooks. These minor pieces find good squares early more easily, and getting them out clears the back rank for castling and eventually connecting Rooks.
Try not to move a piece twice before the others are developed once. You will only rarely be able to get them all out before one must be moved again, but this is the goal.
The Chernev book recommended in post #13 is excellent. Also, after that, Fine's Chess the Easy Way.
I do all those things but my games still turn to crap fast.