I've decided to study some theory as I feel I am not improving any more - playing more doesn't help much and my game seems stuck in a rut - when I sleep well I play slightly better but all in all it's become clear I need edification - well, I'll see in a two-year time. In the mean time let me share.
A nice position from Yuri Averbakh's book Chess tactics for advanced players - when you know there is a winning solution for white you'll probably find it - although the position looks dire: the rook on f4 is attacked and black also threatens mate with Q to a1. (Averbakh calls it defence against a double attack - so you have to find something to deal with both threats and luckily there is such move - and, as a bonus, it's a winning move.)
I like this puzzle because there are just few pieces on the board and so it seems simple - but is it? You'll see.