Shopping for yourself is definitely difficult with small children. Try short amounts of time with promises of things they like to do after you have "mommy's turn to shop." I spent a lot of time in the Disney Store when mine were little, but they had to spend some time in my stores too. We would go back and forth with stores for them, and stores for me. It also helped that we went often enough that they were used to a similar routine on each shopping trip. We always took time for snacks and playing at the mall play areas, too.
Ideally, you need to have regular shopping outings when the kids are with dad or a babysitter. You'll get so much more accomplished, and not feel so pressured to get everything done during those unavoidable times when you must shop with the kids.
Online Shopping. Moms today are fortunate to have this option, so take advantage of it, even if only to get ideas of where to look and what's out there. Use sites that have free shipping and returns, like Nordstrom and Zappos.
Budgeting. Keep a separate budget for kids clothes and your clothes. Make sure you actually spend your budget, and don't use it on the kids.
Wardrobe Consultant and Personal Shopper. Love to help women match their outside image to their unique inner beauty.