Ask permission?
My nearly 11 month old daughter sometimes gets extremely upset about things like diaper changes, nose-wiping, and naps...I've found that it literally works MIRACLES to slow down and ask her permission when I want to do something to her. I'll carry her over to the changing table and say, "May I lay you down on the table now and check your diaper?" Or show her the tissue and say, "I notice you have some boogers on your lip, would you mind if I wiped them off?" 95% of the time she lets me do it without protest. The other 5%, I respect her no and try again in 15 minutes or so.
Obviously, she can't understand most of what I'm saying, but she gets the key words, gestures, and most importantly--she gets that I'm ASKING her. Sometimes I DO have to do things that make her upset (in which case I try to be sympathetic but firm: "Yeah, I know you don't want me to do this. It makes you MAD! Go ahead and tell me how mad you are. I'm listening. It'll be over soon."), but I've found that calmly explaining what I want to do, involving her in it, and asking for permission, greatly reduces the amount of time she spends yelling at me.
My daughter also likes to put dead leaves in her mouth! I let her play with them until she puts them in her mouth, and then I take them away but hold them in front of her and say something like, "Isn't that interesting, it's a leaf! It fell from a tree. You can play with it, but you can't eat it, it's YUCKY," and I put it on the ground where she can choose to pick it up again or not. I do this over and over and over and over and over and over again. Eventually, she usually loses interest in the leaves and will stop putting them in her mouth...if it escalates too much and it's driving me nuts, I'll just get her away from the leaves.