Stretch a rubber band over your gallon of paint to swipe the extra paint off of your brush. (If I manage to do this without spilling the entire gallon of paint getting the rubberband on, it's truly a genius idea.
Make your own chalk paint using plain interior paint mixed with Plaster of Paris. Mix 5 tablespoons of Plaster of Paris with 2 cups of paint and 2 tablespoons of water. It may be lumpy, but once you brush it on, it evens out.
Read This Before Painting Anything! How To Paint Over Glossy Furniture Without Sanding! Excellent, Detailed Instructions On Which Primer To Use, Which Paint To Use & Other Important Tips & Instructions!