This guide will cover basic steps you should take every time before you use some website related to trading, depositing or withdrawing CS:GO skins (may apply for other games).
DISCLAIMER: This guide is made only to help you and show you basic skills to not get scammed so I don't take any responsibility if someone actually scams you. All pages shown in screenshots are for demonstration purposes.

Every secure page should have valid SSL license and should stat as https://. You can check the validity of the license by clicking on info/padlock icon next to address bar.





Note: It's very easy to get SSL for your site and there is not any actual security checkup performed nor any check made by other people during the registration process.

Every website must provide information about owner's name, address, etc. while it's registered. These informations are not checked if they are real or valid so that's we need to look and check them by ourselves. For this kind of service, we can use WHOIS lookup at https://whois.godaddy.com
Just enter the page's URL and wait what will come up...
Correct:
Wrong:
... You can see that all informations except country are not valid and owner even used temporary email address

I do not recommend using sites where are WHOIS information hidden or there is something like "anonymous" or "hidden owner" because in this case WHOIS it's not much use.

Note: I recommend using Google maps to check if the address is actually valid and if there is building on address found by WHOIS. Eventually, you can check if Google knows about the company located on this address.

Trustpilot is service when anybody can enter URL and say if they were satisfied with the purchase, how everything goes and tell some tips about that particular site. Primarily you should look at reviews made by users with more than 10 reviews on Trustpilot

If you want to put money into any website I recommend using mainly Paypal or third party paywalls like G2Pay, Amazon, Google Wallet or Braintree. It's easier to get your money back if they actually scam you. Never enter your credit card information elsewhere than in these trusted third party websites!

Pay safe, pay secure

Spread the word! The easiest thing you can do is post in comments like "Scam: http://scamsite.example", and then where you found it!

The advanced action you can take is to use WHOIS to find where was the website registered and report it as Abuse on provider's website. For example, if the website was registered at GoDaddy, contact chat support at https://support.godaddy.com or write an email to abuse@godaddy.com including clues you found about that website.

Huge thanks for reading this guide! If it helped you in a good way then please share it with your friends, comment a suggestion or give it 5 stars! If you are not sure about some particular website, write a comment and I will try to figure it out for you ;)