One main thing for black to remember is to not start playing end-game moves too early. Too early is: when there is any weak group on the board, or there are large empty areas left (e.g. one of the players can keep expanding their frameworks). Similarly, if your opponent plays end-game moves in the beginning, try to tennuki and get a large point. 

In your games, try to care generally more about weak groups and weaknesses (e.g. cuts), and less about territory --- defend your own weak groups, and cut / attack your opponent. Worry about territory later on in the game :) Good luck!