Eastern Europe is a gold mine of tech.

I waited till the Polish-Austrian war kicked off then attacked the Poles in West Prussia, lightly defended so it fell to direct assault with no losses.

Traded that to the Prussians for half their tech advances (mostly agricultural) then took Lithuania and swapped that with them for the other half (the military stuff) and some cash to retrain my army.

Then it was off to Podolia which fell and was traded back to the Poles for their tech and a peace treaty which teleported my now well experienced 2 chevron troops back to London.

In the Spanish War a few years later I picked up Hispaniola and Cuba then conquered Flanders with my Polish expeditionary army and swapped it with the Dutch for Ceylon. Also captured the entire Spanish Fleet in an epic battle somewhere around Trafalgar

By 1720 I have 15k or so a turn profit and am madly upgrading all the plantations and ports I now own.
Ceylon should give me a good jumping off point for India (I'm supporting the Mughals financially against the expanding Marathas).
The only current war I'm in is against the last remnants of the Huron in the NW Territories who I'm using to level up a Canadian stack for the longer term war against the French.

Halfway or more up each tech tree when my own research is combined with the captured techs.

Now if only the AI would give me a reason to have to defend all those islands...