Check for SSL certified sign..The use of an SSL certificate on a website is usually indicated by a padlock icon in web browsers, indicated by a green address bar,changing the URL from http:// to https://.
To check whether a site is legit usually, I do follow a simple checklist to see how well they do, especially when I need to part money with the site;
1) Does the site have a current SSL certificate?
2) Use WhoisXY.com to check the whois information and check whether the contact information matches with the one in the website.
3) In the domain contact details, is there a valid email address.
4) Is there a valid phone number visible, and does it work ?
5) Go through review about them using Unmaskparasites.com and check whether they are scam free.
If I am satisfied with the result then I purchase a small priced article and if it is delivered safely and promptly then I go to purchase my desired product. You also can follow the steps that I do...In general, anyone who is trying to do legitimate business on the web will go out of their way to try and make it clear that they are legitimate. So if a site has not even done the bare basics to give customers enough confidence to buy they're products, then it is almost certainly some sort of scam.