There's plenty of sites, but I kinda like CSGOGem, its an "upgrade" site where it basically rolls a random number between 0-100. Say you have a 65% chance to 1.5x the value of your skin, if you enable over/under you can say it'll roll under 65%, or over 35%.
So if you do under 65% and you get say a 50% on the roll, then you win. You would have also won with a 50% if you had done over 35%

You can also check your previous "upgrades" and see what numbers you rolled, etc.
Can use these to help predict a bit.

I at one time turned $0.50 skin into an Ak47 Aquamarine Revenged FT from just depositing 3 skins worth $0.50 each. I think the lowest value a skin can be to bet is like $0.40 USD
Pretty decent site imo but you can RIP skins.

And as you can see, I had a Gut knife slaughter just a little over a week ago, and now I have a Karmabit lore. \o/
But yea lol

I got the ak hydroponic and I love it. Also I've been buying cheap skins on opskins (like $20-40 under real value) and trading them on a trade site for easy profit. I'm gonna see if I can do some more trading tonight and turn my bayo doppler into either m9 doppler or kara doppler

I absolutely hate trading CSGO items... xD especially with other ppl.
Someone told me to add them for my Karambit lore to Fire Serpent Fac New trade. If they do actually do a legit trade offer and accept my request it's pretty good profit.

Edit:
well he told me he wanted also the butterfly knife, but it's not tradeable and he said he'd take it when it is.
Had me do multiple trade offers after declining my trades and then tried to swap out the Fac New Fire Serpent with a Field tested XD

Smh ppl trying to scam

yeah i've fallen for something like that once, was trying to trade for something FN but it was FT and didn't even think to check. lost like $30 but wasn't really that mad so it's fine.

So i rip'd all my skins on csgogem

hey that's the knife i have

http://imgur.com/a/5kH1J
Throwback to before i cashed out feelsgoodman going from stattrak ak redline to 2.3k D

got a pretty dank ace

Honestly tired of playing CS:GO competitive atm, seems almost ever other game there happens to be someone cheating or really suspicious. I've gotten to the point where I don't even really play ranked games all the much because of it.
I've had people cheating on my team, facing other cheaters on enemy team spinbotting, etc. They're fucking everywhere and it's pure cancer.

At least vac and overwatch are catching SOME of them.

too bad they havent caught you yet