First the compressor is small if you are doing a full paint job but it can work if setup properly. Set your regulator to 80 psi with a water trap and your gun at 40psi with a filter and gauge at the handle, open your fan almost all the way to get a nice long oval shape, and open your trigger all the way. I don’t know what gun you are using. I don’t know what clear you are using, but most that I use never call for thinner in it. It is usually 4/1 mix. 4 clear and 1 activator! If you need any thinner you only put a small splash in it, way less than 10%. Spraying at a higher pressure will atomize the coat a lot better and smooth it out. Check your tech sheet for the clear you are using and mix it accordingly or maybe you just need a better quality clear. Put your first coat on light to have something to stick to and put your next two coats on thicker with your last one being very wet. You will normally get a run or two if you put it on wet enough so make sure it is really wet and no dry spots on your final coat. Wet sand it after a few days and buff it out and you should have it smooth as glass. If you want a show finish, then wet sand the entire car, do not buff it and put three more coats of clear over what you already have there, then wet sand it again and this time buff it to a show finish. There are many factors that could be causing orange peal. Without being there and seeing how your gun sprays and how you spray with your gun, knowing the clear and materials you use and what the conditions are etc it is difficult to say much more. We can only guess with what info you have given us. Good luck.