I'm working on starting up an SR3 game with a group that is completely new to Shadowrun (myself included). Normally in games that I run, I like to encourage my players to put some effort into creating a detailed and thought out backstory. By "encourage," I mean that I usually offer some sort of minor bonus for starting characters that have such a background. In other games, this typically means a little bit of starting XP, or if it's worked into the backstory, maybe a special item that they otherwise would not easily obtain at character creation. It's never anything gamebreaking, and doesn't offer a huge advantage, it's just supposed to be enough to feel like a reward without being overpowered.
Anyway, with my inexperience in SR mechanics, I was wondering what would be an appropriate level offering for my players? I was thinking maybe a handful of extra build points for character creation, or maybe some extra starting karma, or maybe X

worth of gear, etc. Being unfamiliar with the game in practice, I'm just not sure how much of what I can offer without unbalancing things too much. Any thoughts?