Research and develop a business plan.
One of the best things about this business is the low startup costs. For around $5000 you can be up and running but there are some essential intangibles that need to be mentioned
1.A business plan.
www.genbusiness.com has some free information in their "learning center" that is helpful. Windshield repair is fairly uncomplicated so you probably don't need to hire a consultant.
2.a market analysis, some choices made on how you are going to approach your market based on personal preferences and local demographics.
3. Sales training and coaching if you lack that experience. This is the "do or die" aspect of this or any other business for that matter. It's OK if you don't know how to sell now. What's not OK is not being willing to make the committment to learn.
4. A good accounting system. Having this in the beginning saves a lot of challenges later on. Don't neglect the IRS!
The leading causes of small business failure is a lack of a defined business/marketing plan and proper accounting.
I recommend Keith Rosen's "The Complete Idiots Guide to Cold Calling". You can get it at Borders or Barnes and Noble. Although intended for sales of much more complex offerings, there is some very helpful insights for the windshield repair business. One of my favorites is based on the concept of "non-negotiable prospecting", that is, "the only way to build your business is to see enough people as frequently as possible with the intention of presenting your service".
www.profitbuilders.com is Keith Rosen's website, there you will find a number of free articles that are very helpful.