@ Glassoid
As you can see we are still testing ideas, but I would say:
1- Focus on the economical techs ( CS , currency and maybe Calendar ), develop your land and run away from the temptation of beelining Optics for contacting other civs ( your economy will be in far worse shape in the contact moment than if you developed better )
True, col and especially civil service are essential whatever you do. Calender depends on the map. I usually don't research currency that early, the extra domestic trade route doesn't do it for me. Non isolated currency gives you the possibility to get (a lot of) money from others, not now.
2-Make a sustainable REX ( 50/60 % ) and pick the best spots ( you'll have time until the others grab Astro ). Look eagerly for good cottagable land and/or nice food sites for specialists.
Very important, you won't conquer neighbours anytime soon so you'll have to do all the hard work yourself. The sooner you start with this the longer these cities have time to grow to something worthwhile. I think it's worth it to sacrifice some research for this purpose. See also invisible stalks approach in this thread, he went domination and set all his cards on rex not caring too much about research rates or liberalism with very good results. I did some rexing like this in the lonely fred thread, was behind but caught up surprisingly easy when all astro got in and alll my cities picked up trade routes like no tomorrow.
3- You need big cities to balance your isolation. HR is a good friend. You'll also need all the

you can get. Do not overwhip ( maybe only whipping settlers and workers and a ocasional building )
HR is always good but in normal games it's always delicate where you'll want these units (HR or attack) , isolated it's even better, if possible avoid hunting, i popped it from a hut this game
, i immediately stopped connecting the copper to get some warriors build.
4- Unless you want to go cultural ( and maybe even there.... ), found only 1/2 religions top . You'll want a more religious divided world ( more wars, less tech trading, possibility of a backdoor for a later invasion.... ), it protects you better
Absolutely, you need one religion for happiness ,try to actively avoid founding the others. they're almost useless.
5- Beeline Liberalism. Even if you loose the race, Free religion helps with the research and puts you under the radar scope of the AI ( you'll not have the religion minuses , so less probabilities on a war)
This is where monarch and emperor+ differ for me. At Monarch sure go for it and take astro from it,wait with machinery till you can lightbulb liberalism to 1 turn, do it then research machinery, optics and take astro.
I have my doubts on emperor+ as you can see i and also Invisible stalk lost lib race in the lonely fred game, ok it came ridiculously early in that game but it will always be a bit of a gamble since you have to research so much yourself and also have to have a sound rex which will cost you research, we'll have to play emp+ isolated games i feel to come to a conclusive answer, right now i feel go to CS (you can't do without), then turn around and go to astro.Research bonus from FR is not that substantial but relations are so i tend to FR as soon as i meet the others.
6- Prepare a defensive fleet ASAP ( self explainable )
Frankly i never do this when i intend space, i'll trust on my diplomatic skills there, if there is a Monty out there that i can't bribe i'll watch for the "enough on our hands warning", i can always build a fleet then
7-Forget your pride and cave in to the AI demands ( you'll be probably weak until the Industrial age, so don't mess too much around ). Even worse, give the AI all of your spare resourses or trade them. Get friends, but always try to stir a war overseas.
All true and important, i sell all my resources also for gpt.The supplied us with resources modifier takes some time to kick in but it can be the difference between a civ being pleased/cautious with you which is essential. I give in to every remotely reasonable demand (though not to demands on monopoly techs)
8- If you survived this far, now is a good time to think how to win. IF you have a nice chunk of good land, Diplo may be a solution ( big population ). Space may be a nice idea too (in that case beeline computers and spam labs; Internet is a good help too). Or you can take a
tour de force and try a late Dom victory ( tech until the desired unit, shut down research and $rush (US is your friend ). Numbers over quality )
I found out playing this game that domination means planning ahead (even before you meet the others).
9- Enviromentalism is your friend in isolation ( you'll need big cities and in isolation

is your limitating factor ( remember that HR allows you unlimited

and that there are much more ways to

than to

in Civ IV )
I don't like environmentalism, it precludes Free market or State property which are both huge civics. I suggest when going space beeline directly to electricity/radio/computers, then research refrigeration and genetics and the health problems are gone.
10- Nukes are your friend too ( maybe you'll need to stop a launch
in extremis )
I have no idea here, never used nukes , they're a bit too extreme for me
.
There are no wonders that are needed to win in isolation ( some will help, but they would help too in non isolated starts : Henge, GW ,Pyramids, GL,.... ). In fact, probably you won't have even a chance of trying to build some ( like most of the medieval ones ) :Normally it is better to focus in more/better cities than in wonder races.
Agreed, Colossus is cheap but you're cities are so small by the time you build it that they don't profit fully. It's obsoleted by astro and you'll have this tech asap when isolated. This wonder can be effective when financial though.
This is just a catch up of the LHCs so far. I hope it helps ( and everyone is free to add something I could had forgotten of course

)
P.S Maybe someone should write something in the Srategy Articles section about what was learned so far in the LHCs. Volunteers?
You do it