If you have experience in choosing new projects, I think you should use that money to invest in IEO projects in this market, you will definitely get a lot of profits from it. But if you do not have the experience, it is best to buy the top altcoins in this market
Even if you have experience, you should not invest the entire portion of your investment in IEO; Even people with full experience cannot benefit from IEO in this market many times. So I think one third of your investment should be invested in IEO, one third in Bitcoin and the rest in Top Altcoins. I believe you can be risk free.
I'm not sure how you think this scheme is risk free. For sure it is way less riskier than investing in only IEOs than in IEOs, Bitcoin and Altcoins.
However, you should consider that crypto market is very synced at the moment, thus being said if bitcoin will drop - don't you expect alt market to remain on the same level.