Any questions to ask trading platforms before joining them?

Salam Alaykum,

A beginnett here outside the UK & America. I wanted to know, for Halal trading, what are the questions I should ask from trading companies/platforms (ordinary or “Islamic”) before moving forward with them?

Many specific issues are presented by some of the members in this forum, but is there a beginner’s set of questions I should present to these sites/compaies before evn signing up?