I'm speculating that Inno scheduled for this week so people would have it in time for the Summer Event, because events are great trash generators.
Anyhooo....tip from beta
Initially sell low value items without gems frequently (2hours) till more slots open, when you have multiple slots open sell big ticket items with gems and set the timing for 24 hours. This way you will earn more gems.
Yeah, I figured that out right away. The second slot takes 10 trades to open up, so getting a lot of fast turnover at the start helps. Then when you have multiple slots you can work on building up your gems. I'd use one slot to consume the junk quickly and the other to slowly break down the better stuff. I'm looking at down 8 hours rather than 24 though, according to the unofficial wiki the 8 hour is a 25% boost, and the 24 hour is a 50%.
I guess it depends on how much the later slots cost. I'm thinking of down the 24 hours with at least 3-4 slots open. Use the 2 hour slots for the low value gem less trash, 8 hours for stuff that that's 0-x gems and might not produce and 24 hours for the really good stuff.
Goodbye to all the gate of the sun gods & face of the ancients
I'm going to hold on to those for events. I don't even have that many left in my main if any.
My junk items are the coin and supply boosts, the coin rushes, at least some of the self-aids, Palm Trees and Victory Towers, and junky normal buildings. They can fuel new slots. Maybe the weaker attack boosts, since you can't stack them. Stuff like Wishing Wells and Terrace Farms will be gem fodder. The GE buildings in general look like they're good for getting back some gems.
I'd recommend selling one high-value item first, maybe even doing an 8 or 24-hour barter, just to get a couple of gems and a lot of coins, just in case there is some auction item that you really want. Then sell lots of cheap items to unlock slots. Since most people will start by selling cheap items, you will be in the lead with lots of coins right off the bat.
No need to rush it, it's not going anywhere. I'd get that second slot open ASAP myself. You'll need a good pile of coins and a decent number of gems to get anything good out of this anyway, so it'll be better to have as many slots open as possible.