Well, I think the first mistake is that you are not going for the 13 colonies. Taking over the 3 provinces to get them to join you is rather easy and tremendously worthwhile. I did so with almost a full stack in about 2 years, sailing to Georgia, up into Cherokee country, and then up to New France. This is where it got fun.
After taking New France, I obviously got a huge increase in income with the 13 colonies now on my side. I built up a full stack of line infantry, 2 cav, 1 12lbs, and invaded France. By 1720, I had wiped out all of France. Paris gives you a huge increase in income. You can't really auto-resolve the battles when attacking most major countries since the odds are still against you, but just lay seige and let them attack you. That way, you can set up your line the way you want and let them attack you on the field. So much easier to defend. Remember to fold in your flanks when they hit your middle like this: \_____/
It is now 1728 and I own all of North America, except for Iriqois since they have been nice to me. I took Hannover, and the other 3 minor countries on France's border (forgot their name...Wuitembourg?). I have 3 full stack armies invading Spain now. 1 I placed on the coast of Mexico, and 2 on the coast near Madrid. I moved all 3 in at the same time and took both Madrid and Mexico easily, cutting off Spain's biggest income drivers.

Trouble is, I now have Spain's armies rushing back to Madrid (they were tied up in Gibralter in a war with Portugal). luckily that is where I have my 2 armies. Will know tonight if Spain poses a threat. If not, I will have control of all of NA, South America, and almost all of Eastern Europe by 1730. Man, I love this game.
SCP
Eat my crust!
scpgaming.blogspot.com