I've never sprayed panels before so not the one to ask, lol. I've used Halfords paint for the trims on mine though, but been very lucky with the finish I think.
I just gave it several light coatings in no particular order, then the same again with the laquer. Quite lucky that it didn't come out shoddy really 
fair play mate. ive done 3 coats of paint but then when i lacquered it im left with a really abrasive finish and dont know what to do other than to do it again and not put lacquer on!!! 
After the final coat of lacquer, you need to 1200grit wet sand the area. Use a drop (and I mean just a drop) of washing up liquid in say a litre of water to help the paper glide over the surface.
You then need to 'buff' ideally using a couple of grades of cutting paste and either a lot of elbow grease or an electric 'mop'.
It isn't really necessary to sand between coats, especially the base coats. A 800grit paper will remove a dust-coat with a couple of passes, completely defeating the object of 'dust-coating'.
Remember, the area to be sprayed needs a key. Lightly use a scotchpad on the area and the area immediately surrounding to key it. Any marks will be removed when mopped with cutting paste.