how do i do this trill?

[adgjgjg]

I usually don't have problems with trills when doing on two white or two black keys only, but It's a problem when trilling a white and black key (D and D flat in my case), mainly if I use the fingers 2 and 3.
So I want to know what's the proper way to play this and what's the better fingering?

Thanks

[j_menz]

You could try 13, with the 3 on the Db. You could als try moving your hand further into the keys so the finger tips fall naturally about the level of the front of the black ones.

There is no "correct" fingering for trills, just ones that work and allow you to play the other notes.

[xdjuicebox]

You can tilt your wrist [assuming this is right hand] counterclockwise a bit, that helps a bit. One thing you can do is really "learn" the difference in heights by just playing the two notes as a chord a lot and learning how much you need to lift and press down.

[jayeckz]

For me, the fingering would depend on what comes before and after the trill.  In the literature, there are some cases where you may need to use 3-4/4-5.  Not factoring what comes before and after, I would do 1-3.