If you are looking for a good ROI, look and see if the project has a good developer and business plan. See how much the total supply of the token will be and how large the marketcap will be after the ICO. Compare that marketcap with other projects in a similar field.
As an example here is a one I have been following:
https://bitcointalksearch.org/topic/ann-billionaire-token-games-on-the-blockchain-deflationary-algorithm-2065888So this is a Poker/Gambling token and they seem to do pretty well in crypto and have fairly high marketcaps. The project has some very unique ideas to help passively increase the value of the token over time using deflation. They have a solid plan and how to implement it, they aren't being greedy and asking for $millions, only what they need to get their platform started.
Now lets look at price. ICO price is $0.10 a token and there are some great bonuses to be had, so lets look at total supply. Total supply is 3 million tokens, so if they sell all of them $0.10 x 3 million giving you a marketcap of $300,000. That's nothing in the world of crypto currently, this to me has x10 written all over it when it hits the exchanges as the project is easily worth a £3 million marketcap so that would increase the price of the token to $1.00. With the plans they have for the future this could easily have a £30 million marketcap compared to other Poker/gambling tokens which would x100 your investment on ICO price. Also that doesn't take into account all the free tokens you get from the bonuses during the ICO.
That to me would be things I would look for in an ICO