How do Maxing Services work?

So currently I have 4 character slots all filled with 8/8s, I have nothing left to do much except get whites which I can't store due to 2 vaults... So I needed a way to get gold, so I thought of maxing services, can someone fill me in on how maxing services work and what omm/middle men work thanks have a nice day.

You farming enough pots to max any char the customer needs, make a deal, use mm/omm, trade pots = profit.

Do you think I could get people to pay in the prepaid visa cards?

Use some online wallet such as PayPal.

Though, a lot of people try to scam when doing real-world trading on an online game, and PayPal has a terrible refund policy. (Seller always loses.)

For another warning, it's illegal.