Many people have posted small insights into how to play, but I think this game is still new enough that players are still exploring avenues of best play.
This is a delightfully complex game where no simple advice covers all. For instance, Austria is going to get creamed by France no matter what. So what is the best plan for defeat and recovery?
Spain is a tempting target for Britain in the early game, so the later game French intervention is often mooted.
Perhaps there are players who have better insights than I do, but playing many games, I have only played as each faction once, one faction two times and two factions three times. So my 'wisdom' is still in its infancy.