I have painted two bike one rattle can and one using automotive paints (using a preval sprayer ....which is a rattle can you put your own paint in) The auto paint is far more durable.
either way it costs more than you would think. Even spray can you get a lot of overspray (ok I did) and you use up way more can's of paint than you would think
I put over 160 bucks into auto paint supplies and the prevals. It is hard to get small quantities, so you will have leftovers for other jobs. I also alerady had a good mask which is needed.
the work is a lot also this is what i did based on research here and assuming steel frame
1. strip frame to bear metal (chemical stripper) you want no old paint as it causes bumps in the end surface
2. put gloves on...used scotchgard pad on frame.
3. Clean frame with acetone or paint prep
4. coat acid etch primer.\
from now on follow recoat times and temps to the letter
5. Coat of fill primer (pros put a coat of one color on and then a coat of contrasting color to help in gauging sanding)
6. Sand smooth with fine paper 600 grit or so
7. remove any dust
8. color coat (thin coats, at least 3 maybe more depending on color) follow recoat instructions
9. clear coat (thing coats 3-4) follow recoat instructions
I swear my utility bike will get powder rather than a paint job as it's rattle can is getting really dinged up.
As with all do it yourself there is a huge reward, but in this case it is not financial, IMHO
__________________
Life is too short not to ride the best bike you have, as much as you can.