Candles are great. They smell good and they provide a romantic mood but they get messy really, really quickly. To keep melted candle wax from sticking to your glass candle holders, just give them a quick once-over with cooking spray.
Like all clever uses for cooking spray, it seems obvious once you hear it, but I had never thought to actually do this before. Just give the glass case a quick dose of cooking spray (try not to get it everywhere), then stick your candle in. When it comes time to take it out, you shouldn't get stuck with pieces of wax all over the place. If you do, there are some easy ways to get it out, but this is a nice preventative measure. Hit the link to read more.