I agree with Callie that making a sloper is essential for getting a great fit with vintage patterns. However, I also believe this holds true for sewing with contemporary patterns as well. Though a time consuming project, initially, I believe it is worth it. I'm not sure I will make a sloper as my first project, but I will make it one of my early projects ... maybe third or fourth. The only reason for waiting is that I believe my first two or three projects may be simpler garments then the sloper will be.
Here are some additional entries on the Sew Craftful site, which should be helpful to the beginning or returning sewer/seamstress:
How to Take Body Measurements
How to Take Measurements Hints and Suggestions
How to Make a Basic Pattern
How to Make a Pattern from an Original Garment
How to Pick a Starter Vintage Sewing Pattern -- These guidelines may be helpful those who want to start with a contemporary pattern as well.
How to Compare a Basic to a Commercial Pattern
The Benefits of Working with a Muslin Mock Up or Test Pattern