Right then Airbrushes are NOT essential for a good finish neither is a spray gun
As fro styrene hulls,wash down well with fairy liquid or similar to get rid of all the residue that is on the hull from moulding.Obviously if you have some panel wipe(available in most automotive paint factors) wash it down in that it does a far superior job.
Right then as far as rubbing down the hull what I do is simple 400wet/dry to the whole hull,spray on primer grey,give a very light mist coat (translucent)of satin or matt black,rub down with either 6 or 800 grit till all the black has gone,dry off,degrease with panel wipe,spray below water line with red oxide,mask up the topsides using ELECTRICAL 13mm tape then apply masking tape over this.The reason for using electrical tape is quite simple it is 100% guaranteed that paint will not bleed underneath it.Mask off the hull using BROWN wrapping paper,DO NOT use newspaper as the print will come off and ruing your good work,quick denib with 800 wet/dry dry degrease with panel wipe and apply 4 to 5 coats allowing 10mins MAX between coats.If you get a run STOP and wait at least 24hrs to rub down and start again!!!!!!
I allways use Halfords Acrylic paints straight off the shelf they are superb and are hardwearing.Do not try mixing paints as this will lead to a major disaster keep to the same make and type of paints from start to finish.Some of the members here use Plasticoat paints with excellent results,hey I do as well.But the major drawback with this type of paint is that one CAN NOT use halfords paint on top of them they will react.Any other questions just ask,if you are embarrassed etc just pm me I don't bite,others will probably disagree.
One word of advise others will give you advise and say well it work for me heck yes it might but the advise I have just given you is from 25+yrs of spraying
Stavros