where i can invest my btc and i can get a good profit ...with minimum risk? 
I won't be recommending: Ponzi schemes , Gambling websites , Loaning Platforms . (All of them have high risk)
I will recommend starting a faucet if you have enough Bitcoin to do that , you should invest into a programmer/designer to make a good looking website that doesn't use Faucetbox or any other third party and pay users directly , that should bring traffic to your website (and the rates have to be good too) and you will be earning by the Ads .
Running a faucet shouldn't have much risks if you know what you are doing and you are doing it right .
i dont know how much btc i will need about this ...could you tell about how much btc we are talking about
I'm not sure mate , I mean if you are willing to built the website yourself then you will only need money for FAUCET,Domain name & Hosting .
If you are willing to ask a programmer for that then It could cost you some decent amount (check the services section and ask about this job to know the prices from people who are willing to do this for you)