How to play gambits?

Aggressively and with preparation.

Whatever you "give up" in a gambit (typically a pawn or two, but might also be non-material factors like giving up the center), you need compensation for. For this, you need to play aggressively. The reason preparation is even more needed in gambits is because they aren't usually the objectively best lines; essentially, you are hoping to catch the opponent off-guard at some point - for this, you need to know the line better than they do.

I seldom play "true gambits" and I used to never play them...

Then I discovered how much fun they can be in blitz and also the psychological pressure to the opponent that you don't need to play your solid "mainline stuff" on them

learn how to use the initiative

A gambit is usually giving up a pawn for speed of development.  If you hesitate, your speed of development will be lost and you'll just be down a pawn.  So some good goals are:

(1)  Bring out your pieces as quickly and aggressively as you can.  The open line where the gambit pawn was can be useful for this--for example, if you gambit the f-pawn you will often want to get a rook on the f-file as soon as possible and pressure the opponent's f2/f7 square.

(2)  If at all possible, stop your opponent from castling or break up his castling position.  If his king is unsafe, the development edge is much more powerful.

(3)  Try to operate with threats that will prevent your opponent from catching up.  For example, if you can force him to make defensive moves that do not develop his pieces, you can increase your development advantage.  However, don't make threats that he can respond to by improving his position or chasing away your pieces.  In particular, the opportunity to give check is like money in your pocket.  Don't spend it unless you get something for it (taking away castling, gaining a tempo, etc.)--save it for something bigger.

(4)  Don't be too eager to win back the sacrificed material.  Your opponent may well try to "buy off" your attack by returning the pawn or giving something similar (often the exchange).  If regaining the material would end your attack, it's often better not to take it. You may get much more by continuing to attack.  (It's a different story if he offers so much material that you're sure you can win the resulting endgame--then it's generally best to take it.  But if he just returns the pawn for an even-material position, unless you're rather sure you like that position, don't take.)

A gambit is usually giving up a pawn for speed of development.  If you hesitate, your speed of development will be lost and you'll just be down a pawn.  So some good goals are:

(1)  Bring out your pieces as quickly and aggressively as you can.  The open line where the gambit pawn was can be useful for this--for example, if you gambit the f-pawn you will often want to get a rook on the f-file as soon as possible and pressure the opponent's f2/f7 square.

(2)  If at all possible, stop your opponent from castling or break up his castling position.  If his king is unsafe, the development edge is much more powerful.

(3)  Try to operate with threats that will prevent your opponent from catching up.  For example, if you can force him to make defensive moves that do not develop his pieces, you can increase your development advantage.  However, don't make threats that he can respond to by improving his position or chasing away your pieces.  In particular, the opportunity to give check is like money in your pocket.  Don't spend it unless you get something for it (taking away castling, gaining a tempo, etc.)--save it for something bigger.

(4)  Don't be too eager to win back the sacrificed material.  Your opponent may well try to "buy off" your attack by returning the pawn or giving something similar (often the exchange).  If regaining the material would end your attack, it's often better not to take it. You may get much more by continuing to attack.  (It's a different story if he offers so much material that you're sure you can win the resulting endgame--then it's generally best to take it.  But if he just returns the pawn for an even-material position, unless you're rather sure you like that position, don't take.)

i guess my may not be much helpful lol 😅