You can reset by "retiring." You can retire at level 15 or later with two different results.
If you retire and are level 15 to 30, then you will keep all gear and gold, and be reset to level 1 again. This is good if you change your mind on how to build your character, or if you make a mistake.
If you retire at level 31 to 35 (It is not advisable to play higher then 31, as it takes as long to reach 31 as it did to go from 1 to 30, and that time keeps doubling the further you go), then it is a "better" reset. Retiring at level 31+ you keep all current gold and weapons like usual, but you also get to improve a weapon by "heirlooming it" as mentioned in the stickied guide at the top of this forum (Note, in order to "improve" and heirloom the weapon, you need to be able to use it already, so if you do not have any powerdraw, you can not heirloom a bow, etc). In addition to this added bonus, you will also recieve a permanent comulative 10% bonus to all XP gained per tick.
So if you retire at 31+ you become a "generation 2" character, and get 1,100 xp per base tick, instead of the normal 1,000. If you get to be Gen 11 that means you now have 2,000 xp per tick, so on so forth.
I hope that answered all of your questions.
In short: Retire at 15+ if you made a mistake or changed your mind, and retire at level 31 if you want to level up faster for future generations and want a better weapon/horse/ammo etc.
Feel free to ask anything else, and please enjoy the game!