Now is the time to think about seed saving come fall! Certain varieties must be isolated from others, and you will get the most production if you do succession plantings. Think about all that now for best results.
A Seed Saving Guide for Gardeners and Farmers from The Organic Seed Alliance is almost a small botany and how-to text book. It is complete, if you want that much information. I highly recommend it!
Sheryl Joy of Native Seeds/SEARCH wrote about seed saving in the home garden. She offers up her own experiences and subsequent advice in Saving Seeds in a Small Garden.
Southern Exposure Seed Exchange also has a great post about Garden Planning for Seed Saving.
So before you draw a single map or order a single seed, know what plants you want to seed from, and how to grow them.