I save tomato seeds in the most casual methods. I tell the story that some varieties got into my little collection because I sampled a tomato in someone's garden, came home and scraped the seeds off the front of my shirt ...
Here in my backyard, my tomato seeds go on a paper towel and sit on a table on my covered deck. No, they weren't carried here on my shirt ... maybe my shirt pocket
I have a real advantage for seed-saving in that it seldom rains during the summer months, the afternoon humidity usually falls below 20%, and that table invariably catches about 2 hours of sunshine, each day. The paper towels and seed stay out there as long as 3 weeks. Only once, has a house sparrow decided that tomato seed is edible
Once indoors, the folded towels go in Ziploc bags. The system works okay. I have noticed no drop in germination rate after 2 years. At 4 years in the bags, I've gotten into trouble! My casual technique is probably too casual for most gardeners. Remember, this is in a semi-arid climate.