Wow...so much wonderful advice!!! One thing that I haven't seen mentioned is...the iron is your friend!!!! Make sure you press your seams well....it can make the difference between having a garment looking like "homemade" and something out of a high end clothing shop.
There has been a lot of measure measure measure advice. I would add to that...if you have someone to measure you, take advantage. You will get much more accurate measurements.
Most of all....relax and have fun!!
Patti