Mulligans
General Mulligans
Firefly, Hench Clan Thug, Raiding Party, and Myra's are kinda obvious, you want to curve out and have gas to find your huge tempo swing turns or find your burn (and maybe even spiders). You ALWAYS keep Raiding Party and Myra's in every matchup no matter what, those cards carry this deck. Prep is in a way more valuable than Fal'dorei so you should be keeping the prep more often than her. Side note, if you have Edwin and Prep in your mull, it's prolly a good idea to keep both, especially on the coin, as you sometimes you can draw fan or better yet Raiding Party. When you have Myra's in hand it's time to dump, play super hard for tempo where you can, chip in that damage so you can reload and hopefully close out the game in the next 1-3 turns.
Aggro Mulligans
Just the tempo cards, Fal'dorei is too slow even in these matchups unless your mull has your turns 1-3 spelled out for you. Try to save backstab for meaty minions vs. Odd Rogue, unless you know you can afford to use it on 1-drops and/or you can kill their one drop and meaty minion if you have your blade out. Evis is good for killing those minions as well vs. Odd rogue and Hunter. If you're seeing Odd Pally like me, then keep fan.
Control Mulligans
Same as General and same for Combo as well. Fal'dorei's are worth more in this matchup. If you have Deckhand vs. Priest or Warlock it's not a bad keep and turn one play (but toss if you have Firefly, it's still far superior).
Very heavy tempo deck. If you’re going for value you’re doing it wrong. You mainly want to curve out and gain lots of stats early on the board, then burn them out with your finishers. You can try and sub Greenskin for Zilliax. But the deck really shines in you drawing your blade (hopefully from Raiding Party) and then playing 1 cost Dread Corsairs, or even 0 cost if Greenskin buffed your weapon. All the other cards are just trying to support and achieve that goal that goal