Um, I guess recycling is the biggest thing you can do. Also keeping away from harsh chemicals, and using organic, or at least "safe", ingredients instead. Like using vinegar water instead of Windex or ammonia to clean windows and mirrors.
The usual things.. but I'm always proud of myself when Christmas comes around and I pull out my 10 year old beautiful fake tree, I put presents in gift bags from years past (I reused the ones in good shape) or I wrap gift in newspaper with bows... bottom line: we have very little trash at the curb compared to everyone around. I would hate to work for the waste company after gift giving holidays.
My daily tip is: GO paperless!! Do all your billing online and stop paper bills and adds you don't want.