I learned to play chess about 2 years ago. I played off an on for awhile but have been playing regularly here online since April.  As someone who is still a newbie by most standards, maybe other newbies can learn from some things I have picked up. I am sure there is much to add here but these are just some things I picked up.

1.  If you want your game to improve, stay away from the blitz and timed games in the beginning for the most part unless you are just bored. I played tons of games and never cracked the 1300 level and was usually closer to 1200.  Blunders should not be part of your chess strategy and when you are rushed, you will blunder.  Someone on this very forum told me to play the correspondence games and I have never enjoyed chess more and am now over 1400.  I blunder a lot less.

2.  Castle.  Maybe that is too basic but when I look back at a lot of my losses, it is because I did not castle.  Also, try any and everything to keep your opponent from castling if you can do it without losing a piece.

3.  Don't let your opponents pushed, deep pawn haunt you because it will if you do not deal with it. It may not haunt you anytime soon but somewhere in the latter part of the middle game, you might find yourself in deep doo-doo because of one pawn. Think what it would take beforehand to stop that pawn from advancing instead of trying to deal with it after the fact. The opening is usually the key.

4.  Think outside the box and don't be afraid to sacrifice material if it leads to the greater good. Watch great players against lesser players and they do this often.  I have NEVER lost a game when I intentionally offered a piece to my opponent in exchange for excellent position.  Sometimes my opponent does not take the bait but that is ok because I have them thinking and I still got into a better position. Often, it is just an issue of getting one pawn out of the way so you can be a few moves away from checkmate. I have even defeated the chess.com computer after sacrificing a knight in the middle game to open up the 3 pawns protecting it's castled king. Of course, you only want to do this when you can see several moves after that which puts you in a superior position.  

5.  When you make a bad move, don't panic.  Example:  Your opponent slides a pawn up to take your knight and you realize that no matter where you go with that knight, you are going to lose it and not get a piece back.  Look closely at the board and see which of your opponent's pawns nearby is most bothersome to you and use that knight to go for that pawn.  I have won games doing this too. Don't just move something else and assume your knight is wasted. 

That is all I have for now. Will write again if I get to 1800!

6. Before moving, consider every check, capture and threat both for your opponent and yourself.

Yes, but for me, that is easier said than done!

7. Always assume your opponents will make the best moves when analyzing.

 Chess aint easy!