Mulligans
General Mulligans
Definitely go for a 1-drop mulligan and 1-2-3 curve. If you are on coin you have more freedom.
Depending on the meta Murloc Shaman might be the ultimate aggro deck sporting the new cards Sludge Slurper, Scargil, Toxfin, Soul of the Murloc, Underbelly Angler.
Apart from standard murloc package I have included 1 copy of Likkim because 3/3 weapon for 2 mana might play a deciding role to keep the control over the board in some aggro matches. To assure the 3 attack of the weapon deck has 5 overload cards (Lightning Bolt, Sludge Slurper, Feral Spirit). Feral Spirit is run to protect existing murlocs on the board and tempo swing, kind of 3-mana Saronite. Lightning Bolt is run as a finisher or board removal.
Hex is not included given there are 2 Toxfin and 2 Lightning Bolt for removal which are both more flexible and cheaper.