A student of mine, Zac, (MuskieMan33), graciously agrees to be the "case study" for this discussion of typical mistakes at the U1200 level. I examine a few of Zac's recently completed games, and then I critique three of his games that he plays in real time on the Chess.com "Live Chess" server. Lots of things to chew on: opponent's threats, pawn breaks, squares, planning, and (of course!) coordination and undefended pieces!
Thanks to Zac for volunteering for this video and putting his play on display for instructional purposes.