Investing is pretty risky in bitcoin, because how unregulated it is.
I would invest max 1 or 2 bitcoin and keep the other 10 bitcoin save.
Perhaps 1 bitcoin for passive investments like investing for gambling bankrolls (satoshidice and bitdice are good websites to do this, you can split between these two, or you can find even more if you want to split more, if you want more suggestions just pm me). Or loans on exchanges (i think bitstamp allows you to loan money to people who want to short or trade on margin, but I never tried this so i don't know how this works and how save it is).
The other 1 bitcoin you can trade actively if you want to actively trade. If you're good at poker or know a lot about sports you could use poker or betting on sports, which are both slightly risky, but better than normal gambling. I would not advice regular gambling, as you'd more likely lose money than gain money. Even though I invested in gambling websites and make some money from losing gamblers, I never advice people to gamble. Luckily not everyone listens to my advice.
You could find some other investments/startups to invest in, but research them before you invest. If you find any promising investments, let me know, I might want to invest in those too, if they look profitable enough.
HashOcean also looks promising, although I would be cautious with investing too much, I think they look legit, but I have no experience with them yet, so I plan on investing a small amount and see how it goes. They mine altcoins with Radeon R9 cards and sell those for bitcoin, the payout seems to be fairly consistent.
So far, the most profitable for me has been investments in satoshidice and bitdice. Although you never know how much you make because it depends on two things:
1) How many people gamble and how much bitcoin they gamble
2) How much luck the gamblers have, on some days they might have so much luck that you actually lose money, but since you have a house edge of 1%, in the long run you will earn money. (out of every 1000 bets they make, you win 505 times)
If you invest in those, you'll see over the course of a month or so you'll have some profit. Those are my long-term investments, so that I can get some passive bitcoin income.
They won't make you rich overnight (but no investment really does) but they will give you some long-term profit.
agreed with you, if i have same amount like that , i would be invest max just 30% from my bankroll. and there are another gambling sites which you can invest, example in Cryptogames and Justdice.
and profit is for sure !! 
