The rule is user with the newer coin always sends first. That way if you get scammed, you can always turn around and mine your coins again. I'm not sure why you guys are sending older coins first, since if you get scammed, you probably won't be able to mine them back.
Whatever you do, only conduct business with brand-new accounts so you can maximize your chance of getting scammed. Don't deal with Hero members who have a past history of successful trades.