Although it is helpful to do it once in a while, don't get discouraged by lowbie PvP!! The lower level BG brackets are absolutely infested with twinks, any of which can one shot all of your characters simultaneously. Every I level up to the next level bracket, I keep telling myself "there will be less twinks!" or "the power gap will decrease" it seems to only get worse. Now, I only do a 3 box and a 2 box, so if anyone 5 boxes in lowbie PvP and doesn't get destroyed by twinks, please tell me your secret :P

If you want to practice at PvP, I would recommend simply ganking any player of the opposite faction you see while questing, and saving BG's until at least the 50-59 bracket. There are a few twinks, but their number is SO much smaller than the earlier levels. In the earlier levels you get cussed out simply for not being a twink, let alone bringing in 3-5 non-twinks into a 10 man WSG :P

My favorite PvP bracket personally is 60-69. At level 69 I stop levelling and grind out huge amounts of honor so I can buy some purples as soon as I hit 70. The 70 bracket has it's own level of "twinking", as in you are a fresh 70 in greens/blues against full S3/4 players.