What's a good middlegame plan in this position?

I had this position in a blitz game and had no idea how to proceed. I couldn't think of any middlegame plan at all.

It's black to move. What should I be doing in these kind of positions?

When you don't have anything to do, look for strengths and weaknesses. Your opponent has a hole on c3, try to put a piece there. However, you cant. Then, look for more weaknesses. Their pawns are all on light squares. You can look for counter play with a5 and a4 to break the pawn structure. Finally, look for strengths in white's position. Their strongest piece is their knight on f4. Then, you can attack it while improving your queen's position by playing Qc7. Of course, you also do things like moving your rook to the c file. Always remember to look for strengths, weaknesses, how to improve your pieces, and how to displace your opponent's pieces.

Thanks for your answer! I never thought about any of those things, but they make a lot of sense now.

That hole on c3 stands out a lot. Find ways to make attacks on the files, and try to deactivate their good pieces, which @Oliver_prescott said,  is the knight on f4

the pawn on b3 is also a "hook." You could consider a5-a4 along with doubling on the a-file

I would probably start by playing b5 to prepare a future c4 pawn break. You have to time this carefully though because your pawn on d4 could become weak. So you should only go for the c4 advance after you have first maximized your pieces. You also have a nice central outpost on e5 for your pieces so at some point you can play Ne5 for example.

I'm thinking that, as has been wonderfully suggested, moving Qc7 is an awesome backup to the bishop, if white moves their Q to maybe g3 to defend their knight, what can black do next? How about Ncb4, threatening capture of the pawn on c2, undermining the pawn structure & threatening the Ra1. Depends on where where white puts their Q, but if it's defending the knight and pawn there's definitely potential to do damage. Just some ideas - probing, finding weaknesses, don't know until one tries

Thanks for the ideas everyone! This has been very helpful.

I particularly like the ideas of Qc7 to create a battery, a5-a4 to hook on to white's pawn structure, and Nb4 to put pressure on the c2 pawn.

In the game, I couldn't come up with any of these ideas, so I just immediately played Ne5 to try to trade pieces and move into an endgame.

I kind of knew that what I was doing was bad and that I shouldn't just be trading pieces for no good reason, especially when I have a space advantage, but I couldn't come up with any other plan.

This is definitely something I need to work on.

I don't think black has anything to play for here... probably...d4 was premature.

...a5 seems wrong.  After a4, black's minors aren't so good.

I would play ...Ng4-e5 and hope white has nothing.

You have a space advantage on the queenside so it is best to attack there. You can see that he has several dark square weaknesses, the most prominent being c3. You could improve your dark square bishop with the maneuver Bc7-a5-c3. Then you could move your knights into outpost squares like e5, c3, b4, and e3 (when his DSB is traded). Then you could move your rooks to the queenside and push b5 and c4.

What about catching the black Knight on f4 with black bishop and then moving the Knight from f6 to d5 (the pawn is pinned) and next move to c3? 

I agree with trying b5 and c4 if you are desperate for a win, but I suspect black will score better by controlling at and hanging for a draw.

I wonder how white tricked black into exchanging the light squared bishops.

I agree.  Trading light squared bishops made your position really difficult.

I had a game like this recently that I’m actually still playing. I will post on here regarding it once I’m done because just like you I had no clue what to do.

Nb4! Attack the c2 pawn and after he goes Qg1 b5! Play on The QueenSide!