You can get a great finish on cans if you do it properly, but it's very tricky to do properly, here's how I do mine:
Wet sand down to 240, then 400 then 600
Clean + Dry
put on a 'piss coat', basically just put enough paint on until its covered (not too much), and sand off all the paint with 600 grade wet n' dry, this will ensure it's all even.
Clean + dry
Primer x 1 or x 2 doesn't really matter
lightly sand the primer so it's not so shiny anymore using 600 grade again
Spray around 3 - 4 layers of medium coats (Light coats and cans don't work well - and you don't want it to be too thick for obvious reasons) - You can sand between these coats, but generally it wont make a difference. Also you can pretty much put one coat on after the other - there's very little flash time on monday day aerosols.
after it's dried for say 2 days, use 1000 grit wet n' dry and WET (very important) sand the paint finish carefully until it's dull (careful not to sand too much and go back to primer - and keep the paper wet).
Lacquer about 5 layers on (the more you do, the deeper the shine, and more hardwaring it will be.)
after you've left that all to dry, wet sand with 1000 again, and then finally t-cut, and polish them, they should look perfect now
Hope this helps, I've done the bumper strips in this way, and if you spend enough time you can get them looking perfect!