Shop throughout the year, it's never too early to start. The after Christmas sales are great for the next year and for family you won't be seeing till a few days after Christmas. Make good use of any clearances and sales over the whole 12 months.
Make a budget and stick to it. We have a maximum price limit on every present, if something is over the limit we either don't buy it, or talk to another family member and go halves in the gift.
Make you own gifts. Last year all my daughters friends got homemade play dough in different colours and scents, they all loved it and it only cost me about $2 for 6 gifts.
Remember little kids are just as happy with a small inexpensive present than a huge one that cost a fortune. Check out cheaper shops like the reject shop, you can get some great bargains. Also remember you don't need brand name paper, decorations, snacks etc, you can get these at the cheap shops too.