Asalam Alaikum,
Before I moved to Pakistan, I spent a lot of time trying to sew shalwar kameez suits. The problem was that I had no experience and I couldn't find any directions online that were easy enough for a novice to understand. So I have decided to make my own tutorial, and hopefully it will help any one that wants to learn to make these beautiful and very comfortable suits.
Your first step is to find the cloth for your suit. If you live just about anyplace in Southeast Asia it should be fairly easy to find shops or a market where they sell matched cloth for your suit. If you live in the US, there are often shops in large urban areas(especially where there are large Indian/Pakistan communities) that sell ready made shalwar suits, and also un-sewn cloth for shalwar suits, or saris.
If you can't find a shop near you then your local fabric store should be able to help you find something nice. You could get a printed cloth for the kameez and a plain for the shalwar(or the other way around), for the duppatta you should try to find something that has a lot of drape.
In this picture, on the left is the shalwar cloth, in the middle is the kameez, and the right is the duppatta. The minimum size the cloth usually comes in is 32" by 96", although fancier suits are generally larger sizes. Cotton or lawn cotton suits are the most common for daily wear in many areas because of the climate.
Links to Tutorials in this series-
Simple Shalwar
Simple Kameez part one