i can tig weld and paint, im a made man lol
ill tell you what i do but no doubt someone will either correct me or suggest a better way.
first of all get yourself some pre paint ( just a liquid that gets all the crap of your piece of work) primer, paint and laquer
1.get some fairly coursde wet and dry (cant remeber the best grade but im sure someone else will suggest some) sand down you piece of work until you get a matt finish and it is very smooth. You could even go as far as taking all the old paint off but i never do, unless it has already been resprayed before then you dont know what kind of job someone else has done then i recomend you do sand back to the bear piece of work.
2. clean all the dust and grime etc with the pre-paint and a very clean lint free cloth. Spray thin even coats of primer, make sure not to go mental as you dont really want it to run but if it does your gonna sand it anyways. A couple of coats of primer should be enough. do a visual check to make sure everythin is coated evenly. make sure that the primer is properly dry and hard.
3.grab a less course wet and dry than what you used first then rub down the piece of work gently until you feel no bumps or pimples in the work etc and it is smooth. use your pre-paint to get all the dust off with a clean rag.
4. spray your paint evenly over your work. make sure not to much coz you really dont want your paint to run. doesnt matter if you dont cover all the work in your first coat. wait till this is fairly dry then spray another coat. repeat this process untill your happy that the piece of work is covered evenly. get yourself some fine wet and dry and a bucket of warm water. wet sand your piece of work using plenty of water at a time. do this very gently and only till the paint is smooth to the touch (this will prevent orange peel when it is finished) once your happy with the finish (dont worry if the paint looks white or has gone a different shade the laquer will clear this up)
5. clean the piece of work to make sure no dust or grime is present. spray your laquer like you did your paint, thin even coats. Be patient as messing it up now will definalty not be a gud thing. once your happy that all of the work has been covered evenly leave to dry ( i suggest over night as this will remove temptation to mess with it) wait for a couple of weeks before you tcut or polish it as you want to make sure the laquer has hardened properly.
as i say this is what i do and it seems to work a treat, im self taught so i dont know whether this is the best way or not. im sure if im wrong someone will correct me.