What really helped me initially was playing an archer class (not xbowman) back in Native. Light armor, just a 1hand for melee defense. It was get better or get womped. I'm still outclassed by players more skilled than I, but those are exactly the players I love to fight most. Getting raped by HarmlessPeasant and IMmt all day everyday.
I don't really have anything else to offer that hasn't been said already: practice, practice, practice, and knowing your opponents style, as dexx touched on. Against bots, in the duel server, or just playing more defensively in siege/battle.