Just looking for some improvements, especially positional ones (:

Well you won in the end, so there's that.

As far as feedback for improvement, you're not punishing your opponent for dubious opening play, nor are you properly assessing forced continuations. and missing easy tactics.

After 4...Bg4, you're already winning with 5. d5! Which will force Black to concede the Bishop pair, and a crucial defender of the Queenside where you have some space, or be forced to give up the c6 Knight entirely with the line 5. d5, Na5. 6. Qa4, c6. 7. b4! and the c pawn is pinned to the g4 Bishop, and the Knight has no squares.

The other moment is when your opponent played 11...b6. Which allows you to deflect the Bishop away from defense of d4 with 12 b4! (Funny how b4 is the winning move a couple of times this game.)

I.e. You should spend some time to calculate the attacking moves first even if they look bad or seem to drop material at first glance with no apparent compensation. All in all not a bad game however, and a good win over an opponent 100+ rating points higher than you.

Just copy the game URL at top to post a game

You could've played 25. Qxa8

5 Bf4? loses a pawn.
12 b4 wins a piece,
15 Bxd4 wins a pawn,
25 Qxa8 wins a rook.
There is not much of positional improvement here, only missed tactics.