Ive had some success with a venture capitalist approach. I buy up all the new altcoins that come out for really cheap. most of them dont end up going anywhere but the few that do make enough money to cover my losses plus gain me a couple bitcoins in the wallet. go out there and try new things. only you can decide the best strategy for you
Yes its good to buy multiple coins when the price is really cheap and even if not all but some coins performs well then it will give you good profits and it will also recover your loss of investing in those coins which didn't perform well.
Investing in multiple coins only lead to loss most of the time. Let's say that you got a coin that pumped up, the profit that you'll get from it will only recover your loss from the other coin investments. It's not profit at all. You'd be wasting your time if you continue to do this method. The only way that you'll get profit from this is when the majority of the coins that you bought has pumped up. And based on how you choose your coin (you said when the price is really cheap), I really think that you'll lose money.
Cheap coin doesn't guarantee profit. Most cheap coins have already been dumped by investors or the developers have already left. It's rare to see something that is booming in the market but has a cheap price.