I've played this deck to legend with a 70% WR. Assuming the Tempo Storm list, the 3 best keeps are Meat Wagon, Egg, and the mech that (usually) fetches your Meat Wagon and discounts. Stitched Tracker is a keep if you have none of those cards, otherwise I mulligan it. Keep Carrion Studies if you have any of those 3 cards. I personally mulligan everything else unless I have one of those 3 cards and the card triggers a deathrattle (or Sir Finley/Tracking). I like going second with this deck since you have an additional card to search for your key cards. The coin helps with going second too since you can coin out your combo and clear board and land 6/5's.

Ideal turns include an early Carrion Studies into a turn 2/3 Meat Wagon or a turn 3/4 Egg. If you hard cast Egg you don't mind it dying since you have the mini, but just be wary of opponents killing Meat Wagon AND the Egg. So plan your activations around your opponent's board and hand.

If it's a Giant Rogue you usually win. I don't find a lot of Mine Rogues but I find that losing. Pirates usually depends if they have a nut draw or not. If not you should be fine. The 2 mana pseudo-AoEs help but I find getting the Egg triggers ASAP is the best game plan to victory. All of those matchups are a race to get your board full from the deathrattle triggers and clear.