The buttons are very simple. The arrow keys and Z, X, C, and V. Z is Action1, X is Action2, etc.
Always sell things for 120-130% the base price. Do the dungeon as much as you can to get items to sell. When you hit a game over, hit a payment day and don't have enough money by the end, in the demo you go to the main menu, in the full version you go back to day 2 keeping your Adventurer's level and I believe money. I've gotten to the third payment day and it's pretty simple so far.
