overconfidence

does any1 have any advice on how to stop being so overconfident after winning a few pieces? 

The better your position is, the more careful you should be. In my (much) lower Elo days I got quite a few wins while down a huge amount of material by setting up a sneaky checkmate threat that my complacent opponent failed to notice until it was too late.

For example:

(Opponent's last move, after my Kd3, was ...Qxd7??, capturing a "free" rook.)

If you are ahead in material, but don't feel comfortable with the position of the game, then pull back to defend your king, without crippling your own movement, and try to start picking off your opponent's pawns. Once you get ahead by a few more pawns then trade down the major pieces until the opponent has none. You will then be in a better situation.

Remind yourself of the many occasions where overconfidence lead to disaster.

Additional advice: don't resign in a winning position, like here:

https://www.chess.com/game/live/139152027658?username=wreckard

Once you are ahead in pieces, change your plan.

Instead of trying to grab more goodies, now that you are ahead your plan should be to stop the opponent from getting any counter-play. Prevent him from climbing back into the game.

Trade his pieces off... NOT by chasing them around the board, but by putting your own pieces in powerful commanding positions, so that the opponent will come to YOU with trades, just to get rid of them.

Every pair of Knights or Rooks removed from the board reduces his chances to cause trouble. An advantage of seven pieces to five is nice, but an advantage of three to one is even better... even though the difference is two in both cases.

I have always been overconfident and even arrogant. To my own fault.

Think like this:

“Now I just need to trade down safely, defend carefully, and make no big mistakes.”

I usually find my blunders are the best cure for any over confidence. But seriously, some players are excellent front runners and wont let you back in, some people trade blunders back and forth all game and others might let slip a stalemate or forced mate if you battle them to an endgame making the conversion as hard as posible. I have hung checkmate and stalemate in a forced win, also escaped with wins and draws when I was dead lost. You have to lock in as they are the same rating as you, even if they have been blundering more often.