I've always found the following to give good results. Wait 5 mins between coats in warm weather and 10 when its colder (like now)
Wet sand with 600 grit to give a key
1 or 2 light coats of primer with 5-10minutes flash off time between coats
Wait 5-10 mins after last coat
1 or 2 light coats of colour, you are only looking to colour the part with the minimal amount of paint possible. Don't be tempted to lay the colour on thick as it won't make it look any better
Wait 5-10 mins after last colour coat
First coat of clear should be almost a dusting to give the subsequent coats something to stick to (this will help prevent runs)
Wait 5 mins
Give the part about 2 or 3 coats of clear waiting about 10 minutes between coats
Don't let the previous layer of paint fully dry before putting the next one on. This is what makes paint flake off in layers as the coats need to be tacky in order to properly bond with each other.
Leave the paint to cure for about 2-3 days, to get a perfect finish give it a light wet sand with 1200 grit then use a cutting compound like G3 to get rid of the sanding scratches and finally a polish with your favourite product.