Chess: Efficient training for recreational players
Chess.com has a tactical trainer which I've found very good. It's available through their iPhone app as well as their website, although with a free subscription you're limited to 3 puzzles per day.

http://www.chess.com/tactics/

Each puzzle and player has an Elo rating, and if you solve the puzzle then both the puzzle's and your own rating are adjusted, and you're given another puzzle of similar rating.

Aside from this, record your games and go back through and have your opponent point out errors. When you're playing a game casually and it's clear you're down in material and position position, just concede and start another game. At that point you're just playing to hope your opponent slips up, which isn't a very good strategy.