Not all DIY projects are created equal. DIY can save you money, but they can also end up being more expensive. My projects tend to be because I end up finding more than I need because there is so much fun stuff in the craft store! Planning ahead is key. Set a budget and make a list of the things you need.
1. Start looking early. I find that doing things early not only cut stress in half, but I then you are able to shop around and find deals on all of the materials you need.
2. Pick materials that are inexpensive. If you have a decent size wedding, you are going to find that you are probably going to have to make more than a few centerpieces. The cost of materials can add up quickly. Your wedding is a great time to repurpose things you have lying around the house and make them beautiful again. Plus it saves you a lot of money if you do.