Before his invasion of Russia in 1812, Napoleon was caught in a pretty bad situation with the Continental System which really didn't work and damaged France and its allies more than the U.K. So, what could have been done to fix it? Or could Napoleon just adopt an entirely different foreign policy or even a military solution to his problem with the British. If so, what could it be? Also, if Napoleon doesn't invade Russia, what would happen?
Hamburger
At this point its probably too late, especially for a military solution. The war in Spain will continue to be a running sore and there is growing discontent at French control in the rest of the continent. Prussia is starting to feel confident again after a period of reform and coupled with close relations with Russia. Austria was defeated in 1809 and cautious about clashing with the French again but every war is proving harder as France's oppositions learn lessons from their defeats. Also Britain continues to be dominant at sea and hamstring the French economy by preventing coastal and overseas trade. As well as providing funds and equipment for anyone who is willing to challenge Napoleon.
As such the military outlook is bleak. If Napoleon goes to war in the east he may win the next campaign, or even the one after that. However the growing commitment in Spain ties up a lot of troops, reducing the superiority that even enlarged imperial France might otherwise have over a single one of the continental rivals. Fighting with two at the same time would be a much tougher case and will probably, with British support, lead to defeat. There is also no military solution in the west. He can't reach Britain and Spain's terrain along with the defences of Lisbon, Cadiz and Gibraltar make final victory in Iberia impossible. There might be the chance that if he hadn't gone into Russia the US attack on Britain could impose enough extra strain on the British economy that a peace party will emerge but its unlikely. The best bet for an economic victory was prior to the French attack on Spain as now this means that Latin America's markets are now open to British goods, as well as Europe via many smugglers.
At the same time Napoleon has probably burnt too many bridges to get a political solution. His marriage to Marie-Louise may have given him a lasting peace, given more time and a less extreme war policy in the east. Possibly if he had waited to be attacked by Russia then defeated them in Poland another limited victory and the increase in Polish strength may have lasted long enough that Europe would be content with French domination. [If he's willing to co-operate more with neighbouring monarchs rather than seek to cower them].
Steve