At 1200, he should already be familiar with all basic tactics, and know a few openings. When a tactic opportunity arises in his/her game, half times s/he can spot it and use it. S/he still can't think deeply, but 3-5 moves should not be a problem for him/her. S/he still makes blunders, but much less than beginners.
At this level, you have to be patient, waiting for him/her becoming more mature in his/her games. Keep encouraging him/her play in tournaments. Don't over-emphasize any single game or tournament. It's a time ripe for breakout. S/he can stay in the plateau for a while and make huge jump in surprise.
http://www.completechesscourse.com/puzzles.html
http://onemovecheckmate.blogspot.com/