@ Winston Hughes:
Din´t meen the standard approach for isolated starts, was more like my standard approach for isolated starts (sorry for confusion

)
In my experience, this approach proved quite successful, because I never was able to keep up in the optics race (on emperor is´t possible, on deity I tried but I couldn´t...):
- techs for land improvements
food and money for early growth
- archery (defence, i normally don´t go for bronze working)
makes you independent of any strategical resources, so you can concentrate with your early expansion on blocking the AI´s of (not isolated) or on grabbing food and luxus resources (isolated)
- alphapeth-literacy (had no marble, but it´s fairly easy to get the great lib on emperor (eve on deity) when you get literacy fast)
to build the great library. Isn´t exactly needed (in fact will even slow you down because it isn´t in the direct research path) but helps in GP-production, research (and AI´s don´t get it)
- CoL-Philosophy
CoL to keep your economy running while expanding (I usually build only 3-4 cities before CoL and currency, then the rest) Philosophy is lightbulbed to trade it when I´m found (on emperor you normally found taoism, on deity your chances are about 30% in doing so) and to speed GP production (=Pacifism). Even when one AI gets Philosophy first, no problem. The others stop researching it and when one AI has a monopol, he doesn´t trade it of. So you still can trade Philosophy with the rest and it is higly valuated (you get monarchy, metal casting and cash for it in one trade)
-Currency
see CoL
-Civil Service
to build chain-irrigations to speed growth (I´m a big fan of FE (=food economy)) and to be able to switch civics to buerocracy (don´t remember the exact writing

)
-Paper
to trade maps (helps finding the other AI´s) and because it can be lightbulbed and is on the way to liberalism
-Education
it can be lightbulbed and is on the way to liberalism
-Liberalism
you can pick free religion (what you should do immediately when playing peaceful) and you get a free tech. When isolated, take astronomy, because you can start oversee trade. You should be first to do so, and should have quite a lot of trade options and monopols then
Yeh, not much different to "not isolated". Only difference is that math, currency and civil service can be traded for phil and that I would take nationalism as feebe to go to war...
"Is it just a case of getting as far down a single tech-path as you can before the AI arrive, to ensure that you've got plenty to trade with? Or is there more to it than that? And what's your approach once you've backfilled the tech-tree and picked up Astronomy?
"
That summarizes it quite well. When going peaceful, you rely on trade (and tech-gifts to buy friends) and therefore you must have a tech advantage (via specialisation) lots of GS to lightbulb (earyl Phil) and you must go directly for Free Religion to make oversee friends
After astronomy, I normally go for economics - corporation (free maket and one additional trade route) then beeline democracy (Statue of Liberty). In most games (including deity) the Statue of Libery can be build when you get democracy first (the AI´s priorise warfare techs like replacable parts -rifling -chemistry)