When you make any trade on these forums where there is a scamming possibility, such as a leveling job.
Having both sides of the trade contact a moderator would be a good idea, that way if anything happens, there will be a moderator who knows more of what happened then just what someone says.
Also taking screenshots, or getting any other type of proof would be helpful incase your scammed.
Now in a leveling job, instead of paying upfront, giving the payment to a moderator/admin or someone that both people trust is a perfectly good way to prevent being scammed.
If you wana do this and the other side says he won't do that, maybe thats your clue that he's scamming.
Don't trust people that aren't known by you or by others to be safe.