Probably the best way to invest is to find a site that gives you the best price in return. Check out new marketplaces based on blockchain. Its one of the most secure ways
I think this is a nice way to get yourself scammed, there are many sites that makes promises about high returns and then people realize too late that is nothing but a scam, it is better to get smaller earnings since the risk of getting scammed goes down significantly, remember if it is too good to be true then most likely is.
Yeah we know that lots of sites scamming their investors but there is an investment site which is really good to invest. But me i just recomment to invest in altcoin that having potential to increase its value and having good feedback on their project. Do not look on the small value of coin most of them does not exist for long period of time.