While I really hate to suggest this, the best way to make money might be to sell space on newly opened tabs (with an option to turn off ads for something reasonable like USD$24.95 per year).
Mozilla tries this every few years and gets (rightfully) huge blowback. Mozilla makes enough money (through partnerships), the problem is they just spend too much.
The sheer number of phone calls I would get from pissed-off friends and family for whom I installed Firefox would make me want to put a brick through Mozilla's window.
