There are actually two separate naval games. The Battle of the Lakes and the Battle of the Atlantic.
No sense waiting. The forces of both sides are very even in strength and very hard to increase in strength. The Americans have two very capable Naval Commanders in Chauncey, Lake Erie, and Perry, Lake Ontario. The Americans start with divided fleets on both Erie and Ontario. So the first task is to combine the four initial fleets into two fleets.
If you wish to be cautious, put the fleets which have to enter potential enemy regions into passive mod and avoid combat before you move to the region where your fleets will combine. I tend to be more aggressive moving both fleet in a more active posture. Once your fleets join, you will have superiority on these two lakes with just a bit of luck.
For Lake Champlain you need to build a fleet, this is usually a decent first purchase.
On the oceans, there are four naval boxes, New England, Europe, South and Caribbean. This hold British merchant fleets. If you can place at least one raiding ship in each of the four sea boxes you will gain 4 EP each turn, one EP for each sea box in which you have privateers. The British do have some nice frigates with which to counter at least one naval box. Holding your extra frigates in a port which can easily reach the threatened sea box will provide some opportunity to win a few ocean battles.