need advice for painting

Hi!
I want to paint the frame. Should I remove the old coat of paint? How to do it?
What paint can you advice? How to apply it evenly?
PS: It is my first painting experience.

just use sandpaper to blend any spots where the existing paint is scratched or flaking off, bondo any dents, clean and degrease thoroughly, and go over with your color and clear coat.

thanks!
On the video it looks like everything is simple. Hope it will be easy to do!
Should I take usual sandpaper?
What type of spray paint is it better to use? In my local store there are many color options of Krylon paint https://www.mrosupply.com/search/?q=spray+paint

But I do not know if it is a good choice. Can I take any can paint? Or maybe there are special paint for the bikes?

If you want a fuel proof paint job, then you should use automotive paint. Any paint that comes from a can is not fuel proof. Automotive paint costs something like $800 a gallon. Putting automotive clear on it is expensive too. Then you also have to buy the automotive primer, and thinners and all. Automotive primer from a shake can is not as good as primer that is sprayed on with a compressor setup. The shake can primer doesn't stick as good. It chips very easily. The automotive clear it what makes it fuel proof.

if you get fuel on normal spray paint it just goes hazy. once the fuel evaporates spray a little brake cleaner and it'll go glossy again