First thing first. What ever product your using get the TDS info . It will tell you what size tip, pressure , and type of gun they recommend for their product. I have been painting professionally for over 10 years now . Any new product I use first thing is to read over the TDS, then change as I see fit to match my painting style .
It sounds like your compressor is up to the task but your gun is just not setup properly or its dirty ! Even a cheap gun can lay down a decent paint job , but it may not repeat that same job a 100 times like a higher quality gun will.