While one paint color is good, two are even better. Add in some glitter and you have a knock-out DIY project: http://www.bhg.com/decorating/do-it-yourself/accents/easy-home-decor-crafts-and-gifts/?socsrc=bhgpin041314paintedvases&page=2
How to: Dye Clear Glass ANY Color (A New Technique)
AND IT'S WATER PROOF! Remember the Mod Podge + food coloring technique for painting clear glass? That was cool and all, but I spotted another method using Vitrail glass paint and acetone (nail polish remover) that allows the bottles and jars to be used as actual vases, as the finish is waterproof! This treatment provides for more depth of color as well. Head on over to My Design Folder for all the details.