I learned the following from chasing elk in September and whitetails in October & November:
1. Elk are a little easier to get close to than whitetails, but not by much.
2. regular slow elk can spook elk and deer. I've had several stalks on deer and elk busted because the moo cows got uncomfortable with my presence.
3. Terrain, such as natural funnels (etc.) can be used to one's advantage for both elk and deer. Know the land inside and out, you'll find good ambush sites.
4. You can get away with a decent amount of noise stalking elk so long as they don't see or smell you. Also, the noise you make must be natural sounding.
5. I learned wool is king, meaning it keeps you warm and it is quiet especially on those late season hunts. 2010 was the first year I used it, I'll never look back.
6. Most importantly, I learned 99 times out of 100, something is going to go wrong. One must learn to persevere through their own mistakes as well as things that were outside of their control (wind shifting, especially).