Some things I believe:
1. All martial arts are effective.
2. None are "ideal" all of the time.
3. You must be able to adapt- quikly!
4. Its the man, not the martial art.
5. Its not the size of the man in the fight, its the size of the fight in the man.
6. You will fight the way that you train.
7. You should be well conditioned.
8. Your favorite move will not work most of the time.
9. The basics work most of the time.
10. Kata is great.
11. Kata is not enough.
12. Too many people believe they will fight like a twenty year master.
13. Too many people learn the hard way that they will not.
There are more, but I'll spare you... :-)