but in my opinion the most effective is participating in the discussion in the telegram group, a good project will certainly have interactive discussions between developers and investors.
It cannot be the most indicator to determine the quality of a project. Many scam projects that the team members were very active to communicate with the community previously, but they disappeared at the end of the day. Active or not the team members can be one of the indicators to analyze a new project, but you cannot make it be the ultimate indicator. However, each project may have different characteristics of team members or developers. Some developers can be very active, while others prefer to communicate once it is necessary only.
Yes, being active doesn't solely the reason you chose to invest in a project. Only see it as one of many good factors to build up a good project profile to analyze but that is it. I know many scam project willing to pay a handsome money to hire active managers and Q&A to keep the community looks helpful and active but that's just a facade.