Ya those are awesome tips. Saying them in front of the mirror while looking in your eyes works really well.
Also during exercise is a fantastic idea that never occurred to me.
A couple other tips are to vary your affirmations around a certain theme. Sort of just free form it around a theme of an area you want to improve.
Also RIGHT when you wake up and RIGHT before drifting to sleep, you are naturally in the alpha state and your conscious mind is not awake giving you access directly to your subconscious mind.
I hope this is allowed here, but I wrote a blog post about this (if it's not let me know and I will remove it, but I basically gave the cliff's notes here
Positive Daily Affirmations