One of the most frequent questions we get asked at Shirtini is How do you keep your white shirts white? Although I don't have the definitive answer for every white shirt, or every person, I can tell you what works for me.
I prefer not to take anything white to the dry cleaner. I consider a little ironing time a fair trade in an effort to keep them bright. I also suggest hang drying your white shirts rather than using the dryer, not just to minimize shrinking but because I think they stay whiter. If you're short on space, hang an extending shower rod in your laundry room like we do at Chez Shirtini. It will also have the added effect of making you feel efficient. As for spots, I avoid bleach, and I've never found a garment care label that suggests it. I usually pretreat with Resolve stain stick and worry about the wash later.
If all else fails, it's time for a new shirt and I know where to get one!