Mulligan for Spirit of the Frog, Ancestral Knowledge, keep Perpetual Flame against aggro, keep Lightning Bloom and Flowrider with frog in hand, and any card draw if the rest of your hand looks bad.

Core:
Lightning Bloom - enables explosive turns in all phases of the game
Zap! - good with spirit of the frog, set up a perpetual flame clear
Command the Elements - try to finish the first step in one turn with high-overload cards to prevent locking your next turn, sometimes you don't even need to finish the quest to find lethal
Flowrider - helps you find Lightning Bloom with frog on board (or anything else), great before buffs, OP as a 1-drop
Lightning Bolt - flexible as early removal or extra lethal push
Novice Zapper - cheap quest proc, adds an extra push for lethal
Overdraft - very flexible, the more you overload the better it gets, required for lethal after bru'kan against high-health opponents
Ancestral Knowledge - great draw
Crackle - almost always used as a lethal finisher
Diligent Notetaker - very flexible, can be used with almost all of your spells, I like it as a one-off
Perpetual Flame - removes most aggressive boards, best used when you can unlock overloaded crystals to avoid major overload
Spirit of the Frog - star of the deck, enables fast draws and fast quest completion
Inzah - makes your frog draws so much better and your OTK so much easier

Flex:
Tunnel Trogg - almost completely changes your playstyle if drawn early but is still so broken to be worth it
Sludge Slurper - cheap quest proc, cute lil guy
Finders Keepers (1) - extra value, gives your deck some variance
Lava Burst - extra damage finisher, guaranteed draw with frog after a 2m spell
Windchill - extra draw and slows down opponent's big minions
Investment Opportunity - extra draw, I don't like it as much since the draw is too random and it often overdraws you with frog
Likkim (1) - can be used aggressively or as extra defense when you're overloaded
Snowfury Giant - easily playable turn 4-5 most of the times