I might be wrong because I am only 1700 rated, but the advice I can give in trading pieces is as follows:
1. Trade when you are up material. The game becomes more complicated the more pieces there are on the board. Trading when you are up material usually makes the game easier to convert into a win. There are some exceptions (like tactics, and etc.) but trading when you are up material is the most important thing to keep in mind as you don't want to let your opponent have chances of winning.
2. Do not trade your active piece for a passive piece. You shouldn't just lazily trade your developed bishop for a knight on the corner, that knight isn't going anywhere!
3. Do not trade if it helps your opponent develop faster.. A prime example of this is when you pin the knight on the queen with your bishop, then on the next move you take it hastily. Keep the tension! The opponent will have more trouble and will waste time playing more defensively to stop your attack.
4. Don't trade when you have an attacking tension on the board. There are exceptions of this and that is when it helps your position or attack. Creating tension is usually better than just taking because it forces your opponent to play passively and defensively. Keep their position passive for as long as possible! That way, you can gain more space and hopefully, deliver a successful attack.
5. Trade when you feel like the opponent's piece is going to be a threat in your position. Pieces has what I like to call a "relative value" compared to their standard value. The standard value for chess pieces are well known (Queen = 9 points, Knight = 3 points, etc.) but the relative value of pieces is much harder to calculate. But to put it in simple terms, I am going to give an example:
There are two bishops, one is trapped in the corner with its own pawns blocking it, and the other is in the center of the board, eyeing every direction of the board. Which bishop is better? Obviously, the second bishop. The 1st bishop is comparable to a pawn while the second bishop is good. And the player with the 1st bishop would be so happy to trade the second bishop to eliminate the threats in their position.
And that's it for my advice! My apologies if the text is unnecessarily long but I hope that this makes you understand trades better. I also recommend watching this video if you are still confused. If you have any questions, feel free to ask! I'll try my best to answer.
how do i know when the opponents' pieces pose a strong threat to me? I often get into a position where i am slightly down in material (example a knight/bishop for a pawn) and i am hesitant to trade stronger pieces like rooks and queens because of the general rule of not trading pieces when down in material, but after losing the game i realize that i should've just traded because their pieces were very strong (but then again how can i win if i trade powerful pieces)
Any advice would be appreciated, thanks!