2) Avoid all the non-related users, who ask for payment or pretend to be a member of well-known projects, as actually, they are trying to Scam you by using different means, like:
If a project has Telegram Community and there is an admin with the name Dan Joe and you get a PM from the same name person, then dont just believe him/her as they can use the same name but you have to verify the user from the community or by cross-check his username by clicking on the user name.
My advice is that you/they should try to minimize the usage of telegram for business related issue because telegram is just like a den of scammers, I have received several messages from those claiming to be part of the team of a project and after I make enquiry in their official telegram group chat they all deny not to know such person and that they don't work for them. Most times this happens when you try to ask of solution to a certain problem you're facing and then boom you'll see your PM flooding your telegram trying to provide your with solutions and at the end they'll want you to give them some of your personal information.
Minimize the usage of telegram? There is nothing wrong with telegram, it's one of the best chatting apps for business that I know, the problem is scammers will constantly use anything functional to scam innocent people, I have blocked over 100 scammers on telegram, they PM me first and that I don't like if all telegram users can adjust their telegram security settings to 'not allow PMs' they will be free. After so many blocking of strangers on telegram, the security settings saved me from a lot of headaches.