Hearthpwn

General Mulligan:  Tracking, Devilsaur Egg,  Candleshot, Flanking Strike, Terrorscale Stalker (if you have a deathrattle card to go with it)

Against aggro decks: mulligan for candleshot, flanking strike, tar creeper, and explosive trap.  

Against control deck: mulligan for stitched tracker, freezing trap, spider bomb

Early game: look for the devilsaur egg + play dead combo or devilsaur egg + Terrorscale stalker.  Try to play another card other than egg if you don't have any cards that can trigger the deathrattle.  Try to save tracking early unless you're getting bad draws and can't combo.  Don't use both of your Play Deads, save one of them for later in the game.

Midgame: Don't cube your devilsaur egg, the other deathrattle have much more synergy with cube.  Flanking strike and your secrets will help you maintain board control.  Try to save deathstalker rexxar since its you're only board clear.

Endgame: Try to end the game by cubing your Mechanical Whelp or Kathrena.  Your win conditions are 1) Recruiting King Krush/Charged Devilsaur or 2) overwhelming the board with 5/5 devilsaurs or 7/7 Mechanical Dragons

Sorry if its a little hard to read, this is my first time making a deck so I'm not that good on it and I don't plan to spend too much time so there will be grammar issues (please bear with it)