I would also go to different risk levels for diversification. Next to coins like Ripple, Ethereum,... I would try to find some more unknown coins.
Check out Bittube for example. They are one of the rare coins with a working product and very fast development speed. Highly underrated atm.
If you would like to go really high risk you could check out also something like Dripcoin, which is a very new MN coin but with unusual transparent and up to so far honest developers.
Overall I have three golden rules for my due diligence and investments.
1. Easy entry
If I don't have to pay much or if I can get in a coin easily on any other route I take it. Why not? Rarely happening though.
2. Working product / very promising business case
Most coins just have promises, even the big ones. If I find a coin with real world usage and an already working product I take it. Downside here is that most of these coins already have a high price. Gincoin for example. Bittube is a gem in this category because it has a working product and low price.
3. Active developers / good community
This is always the most important and promising category but it is also the most time consuming one. You have to join telegram, discord, slack,... and become an active member of the community. Then you can get an idea how dedicated the devs are, how often they are breaking their promises, how well their plans are going,... This is especially very important to figure out very new coins. Dripcoin is my recent example here but I also had huge success with Idealcash. Bought it some months ago for 1,5 Sat in average and sold it for 30 Sat. Still hodling a good bag though.
Good luck for your investment!