Surviving in poor terrain is all about scraping up worthwhile yields

I'm assuming the worst of the worst now, tundra and icey lands. Other bad land types can use some of this stuff though.
First some general stuff for poor land survival.
-Have a food resource, its always important but doubly so here.
-Using farms and windmills to balance food is par for the course
-Tundra tiles can only be improved with farms, cottages, workshops etc if they are riverside! They can however chain irrigate non-tundra tiles
-Still on tundra, avoid chopping forests on non riverside tundra as you will never be able to replace the lost

and health! Plus they can be lumbermilled later on.
-Watermills are the only yield improvment that can be built on riverside ice or riverside (non floodplain) deserts.
-Workers take longer building improvements on tundra, desert or ice. 50% for ice, 25% for desert/tundra, this includes roads and railroads

-Specialists provide the same yield regardless of terrain and most food resources will allow for 2 of them

-Trade resources, both for and away a lot more than you usually would, they are much more rare and can get a decent amount of GPT and 1

makes more difference if you cities are size 7 than if they're size 20!
-Shrine gold isn't affected by land
A lot of what I said above heavily favours a coastal, riverside empire, explained below with more reasons
-Roads take longer making sailing routes preferable
-Longer improvement times make coast tiles more attractive to work in the short term
-Commerce will be hard to come by, instant sailing

to rival civs will help a lot
-Most of the places you can improve tiles well are riverside
-Coast tiles being food neutral will be pretty good in worst case starts and can be boosted by Maoi, Colossus and Financial
-The sea often has food
GP farms are the same to set up, just not quite as good.
Specialists themselves however, take on a much larger role if the land sucks. After all, they don't rely on tile yields outside of 1-2 initial food resources. If the land is exceptionally barren, they can provide a decent enough yield to justify a city but the guys will be popping up a lot throughout your empire.
Settling Great People will have a *much* bigger impact on cities with low outputs!
The Pyramids will perform miracles, but wil probably take a miracle to get
Commerce
Well you may be able to get a couple of cottages down, coast tiles are okayish and resources may exist, no point even mentioning windmills
Luckily trade routes are largely unnaffected by poor land, especially early on.
As such lot of your commerce on this type of map will come from trade routes. Foreign ones will be a great boost, but you can also create a lot yourself if you can settle other landmasses (even 1 tile islands), its suprising how much sometimes.
i.e. Say you have a 10 city empire on one single landmass, with 1 (domestic) route each for giving 1 commerce for a total of 10

. Settling a single city on a one tile island will provide a 2

route for every city on the other landmass, plus have a route itself. Settling this city will instantly provide a total of 12

, 2 from its own route, and add 1 to each of the other 10 cities.
To maximise routes like this you will need 1 city on a second (or more) landmass(es) for every route your cities allow, so 1 base, +1 at currency, +2 if you get GLH and so on. I did however ignore foreing trade here, but it does need to be taken into account.
Production
For the most part, same as standard maps. They'll just generally be worst thanks to less food
The common differences however will be,
-Forest being around for lumbermilling more often
-Watermills on ice tiles
-More emphasis on Engineers and Priests and maybe GPs or GEs
Building Research and Wealth is almost always worth doing at times, but more so in poor land.
On Specialisation
A problem does lie in that the city types will often not be very 'specialised' in tundra start type maps.
Commerce will largely be empire wide or on common tiles (coast),
Production may be specialist (swappable) or mixed improvements (windmills)
GPfarms may well be your production or science output cities
You can only go on what the individual city does best, but the difference between best and worst will be narrow when all the cities suck
And yes before you ask, the random map generator hates me
