use a .413 or .411 tip. Keep the wand about 8 to 10 inches from the work, do your cut ins and prime then do a good spray job and you will get more paint on in a nice finish.
Brushing on metal does leave brush marks unless you mix in Flo tro, this actually smoothes the paint out and makes it seek levelness between brush marks. I have had excellent results from this.
Now, the big part of your paint job will be the quality of paint you get. If you get paint from a home center you will not have good results as you would from a paint dealer.
Then, make sure you get paint that is intended to be in a spray rig. For example, Sherwin Williams has its top of the line exterior latex paint called Super Paint, It will not spray well because of its vescosity, but then the next step down is A-100 which is actually designed to be blown.
If all your systems are go and you have everything compatible, you will get a good finish coat.
Remember, prep is 90% of the lasting of a paint job.