This ain't no KTM, but....
I grew tired of a mystery dent that my tank bag hid from me and one day I pulled the bike apart to take care of it.
Unless you have done it before, the end result might not be what you were hoping for... but... couple things.
De-wax the tank with appropriate de-wax or prep from an automotive paint store. Do this BEFORE and after you SAND or GRIND.
After the prep work is done, de-wax before it's primed or sealed. Wet sand out scratches, or re prime and wet sand till they are gone. Hint; anything you can "feel" as far as imperfections, will most certainly also be "SEEN".
Consider just having it done by a chum in a body shop, or find a guy on your local Craigs that can do it right, you might have to stare at that tank for awhile, would be nice if the end result came out of a PAINT GUN and not a spray can, had some clear on it, and you would be proud of the project.
Real automotive quality paint is around $28-$40 bucks a pint, plus the clear and specific sealer.