Only few thing
Are the founders technically capable? Search for other projects the founders have been involved in. If one of the founders is not technically capable, then the co-founders or lead dev/CTO needs to be in order to execute the idea and make up for the lack of technical knowledge of the other team members.
What is the relationship like between the team members and how geographically dispersed are they? Team members with a weak relationship and are widely dispersed geographically introduces a lot of unknowns.
How well can the founders or developers explain their project in plain English clearly and concisely.
Contact the team members with questions through email, Gitter, Slack, etc. with questions.
Try to look for evidence of the team members working together on Gitter, Slack, Github.
Ignore hot buzzwords.
If you dont undestand the project, dont invest in it.
Be wary of team members who try to fluff up their credentials. Its extremely easy to setup a website and make claims regarding previous experience, projects and achievements. Taking money from friends and family to long/short on Poloniex does not make you a hedge fund manager.
Be wary of people who seem less than capable but link themselves to more capable people to increase their credentials.