How do you play in terms of tech trading?

[Plains-Cow]

I like free tech trading unless I'm making a play at Immortal or so and I'm on my own or a small island isolated by ocean with one or two AI while the rest are teching away and trading with one another non-stop on the larger landmass across the pond.

I never trade for basic techs, techs I can research quickly (to preserve trading cap), and prefer to have my vassals do researching for me in different directions and just trade for what they've researched with a tech tree tech that I've steered them away from if I'm warmongering.