Believe in yourself and you'll win a lot more. If you go in thinking you'll lose, you most probably will. That's not just about warband, that's in general, be it sports or some other type of challenges. You'll peak early and not reach high with that kind of attitude (fear, showing too much respect to opponents). Believe in yourself and you can beat supposedly better people at what they're good at.
Of course some fights/matches will be more tense, but hope for the best rather than fear the worst. Mentality is a big part of sports and high-skill games.
Except ivani4, everyone fears ivani4