Great advice about getting your boots and bindings sorted first. Those will dictate board and more specifically board width. Depending on boot brand, you will be looking for something mid-wide or wide. A shop can help you out with that because boot drag is no bueno.
I could give you a big list of things to consider regarding twin vs directional, camber vs other profiles etc, but I would suggest looking at what folks who shred at your local mountain ride. For example, I live in Western Washington (Alpental, Stevens, Baker, etc) and folks who know what's up for all mountain riding are either on directional pow-friendly sticks (Burton Fish, Jones Hovercraft, etc) or twin(ish) hybrid camber boards (Lib/Gnu decks, Never Summers, Burton Flying V, Nitro Team Gullwing etc) depending on how much they like spinning and riding switch.
Go check out the folks who ride like you or like how you want to, and pick a similar style board.