One thing you need to do is make sure they are clean from finger oils and other dirt...
I'd wash them with a soft cloth and a couple of drops of dish washing liquid, warm water and rinse them very well and let dry on a towel...
Then before you paint use a can of compressed air to blow any dust and such off... If you have any cotton gloves it would be better to handle them that way to avoid getting any more finger oils on them...