You do not have to invest more than you can lose. Also you should analyze the project in which you want to invest - team, problems that the project solves, project competitors and more
This is a really good point of advice. I personally look at the team, how much work they've put in so far, what their roadmap looks like, how the community feels about them, and their trading volume. Some of these are more important than the others (I'd say that I definitely weigh a lot how much the community sees them, given that this is a huge world where reputation is important. If a dev team is willing to work to make sure that they are doing what's best for the community then they should have a positive view by the community. Of course, if it's random hate that I can't see where it's coming from or unverified claims, then this means less).
Honestly, it's up to you what you think is more important. For example, do you think that you need to fully be behind what the dev team has in mind for what the coin brings to the table? Do you need a comprehensive roadmap that's rigorous and will push the bounds of the coin? Do you want a reliable volume for the coin to be riding on? These are some of the questions I would ask myself.
