I've started saving seeds of the tomato varieties that I like the most. They need to ferment a few days before drying out. These are "Ukraine Purple". I also saved from "Dwarf Golden Champion" and have a few others to save as well. Today I added "Dwarf Clare Valley Red", which is really good, big, productive.
After these ferment a few days, I rinse the seeds and lay them on a paper towel to dry out. Then they go into envelopes to store for next year.