1. Make the gifts personal. This is #1 for a reason. I HATE receiving body sprays or bath salts or anything along those lines. You could give that to any girl. It has no sentimental value and is not related to me; this shows me you put absolutely no thought into the gift. I always try to give people something that shows that I specifically picked it out for them: something about their favorite animal/color/food, something they mentioned in passing, etc. It makes your friends feel special!
2. Buy things on sale. This is not to sound cheap, but when there are so many sales going on this time of year, it seems silly to pay full price on anything. Plus, then you can get people multiple gifts for the price of one!
3. Shop early. This just makes sense so that your stores aren't out of everything and you don't have to deal with the stress of waiting until the last minute.
4. Re-gift. I see nothing wrong with re-gifting as long as you do it politely (ex. don't use the gift and then try to give it away; don't give it back to the person who gave it to you, etc.). Maybe one of your friends loves the scent of lavender, and you just happen to have received a lavender body wash for your birthday (see rule #1). There you go!
What are your holiday shopping rules?