- The Better Business Bureau (if they are US based or have headquarters in the US).
- The Glassdoor rating and reviews given by current and former employees (including distributors) of what it is like to work with the company.
- The website itself to learn about the company and its products.
- The Facebook page of the company to find out if you have any friends who may be employees, distributors, or customers of the company.
- The LinkedIn page of the company to see if you have any friends who may be employees or distributors of the company.
If you're looking for your first direct sales or MLM opportunity, then I suggest using these sources for the company you are researching to find out if it is a good fit for you.
To save you some time, the following post has compiled the links to the BBB, Glassdoor, official website, Facebook page, and LinkedIn page of over 150 direct sales and MLM companies.
The Ultimate Guide to 150+ Direct Sales and MLM Companies for 2016
I hope this helps in your research!