You have to do a bunch of research yourself, although there are several ratings services that take a stab at assessing ICO quality.

These are the top factors for you to consider:

- What type of token is it ?
- How valuable is the project ?
- How credible is the team ?
- Does the crowdfunding campaign make sense ?

There are several sites that do a good job of publishing ICO details - website information, download link to the white paper, team leadership links (often with notes about whether the LI addresses work or not), plus details on the token sale mechanics - number of tokens to be issued/sold, price, currencies accepted, dates, etc.