Setting aside an area for seed production is something you might like to try. If you want to save seeds from your garden plants, some things like beets, turnips and carrots require growing the plants for two years before they will make seeds. The way I have always worked my annual garden beds is to add a little compost and dig it in each year, making it harder to save seeds from those biennial types. So this year, I plan to set aside an area at one end of one of my annual veggie beds and plant just two or three each of carrots, beets, turnips, parsnips etc. I will also plant a few dill plants, some lettuce plants maybe a few marigolds to get seeds off of this year. The root veggies will get left for another year to make their seeds. By having it at one end of a bed, I can get the rest of the bed all ready for next years garden, and only leave a small area for growing the second season of those biennial seeds.
Read more on seed saving at the Permaculture Research Institute