When buying Steam Keys...

Hello! I am a avid Steam user but, ofcourse, I wish to same as much as reasonably possible on my purchases, at least until I have a steady income.
I am relatively new to the world of buying keys here on Sythe and would like to ask: what should I ask a seller to be safe of my purchase? I mean, the key, and a scan of it?

I have read Steam requires, in case oflitigation, a scan or picture of the cd key, and that's fine, but with the support ticket number written over it! How can tha be bypassed?

Thanks in advance!

 

Sorry, but I can't really understand what you're on about. I know a fair bit about Steam, can you re-explain that again do you think?

 

Sorry for the garbled message I'll try to rephrase is.
I have read around the Net that Steam aggressively deactivates users of keys bought from online resellers (e.g. CD Key shops, Sythe users, etc), either revoking their games or banning their accounts altogether; from what I read, to confirm purchase and/or reactivate accounts, they need Proof of Purchase, in the case of CD Keys a scan of the key part/key voucher with the user's nickname and/or support ticket written in pen on it.

Since I like the reduced prices, how can I be safe from Steam Support inquiries? e.g. do I have to always request a full scan of the CD code voucher, have the seller write my username on it, etc? In short, how to buy keys while making sure I don't get my game disabled or my account banned.