The answer is: it depends. :)
The best strategy is to have a strategy, i.e. decide how you want to win the game in advance. Are you going for a domination victory? Scientific victory? Cultural victory?
Pair this with your chosen civilization and the surroundings of your city(ies) to decide what to build and research.
Are you going for a cultural victory and are playing Ramesses? You should try to build as many wonders as possible and any improvements that'll help you do so.
If you're going for a domination victory with the Chinese though, you should go for military buildings, anything that'll enhance production of great generals and happiness-boosting buildings (since your sprawling empire needs to be kept happy).
For any civilization though you need to balance these decisions with the given situation. Is your city in the mountains but has very little access to food? Then you can safely skip the production-boosting buildings but should concentrate on granaries and water mills. Or are you situated on a tiny island? Then harbors and marine buildings should probably be your preference.
You need to play to your civilization's strengths and balance out your situation's weaknesses. Playing "evenly all over the map" usually works in easier difficulty settings, but you'll need to specialize and focus on higher difficulties. If you set yourself a goal, the question of what to build or research next usually answers itself.
Try to shoot for a cultural victory for instance, and begin by choosing an appropriate civilization. This should be a good experience to show you how playing a focused game can turn out. Playing "all random" is usually more challenging, since it may take quite a few turns until you have formulated a strategy (or you may never get around to formulating one at all).
Anecdote: I just won a cultural victory with the Egyptians, and it was an enormously fun game. I had all of two cities with no military power to speak of (two Infantry units rather late in the game). My empire was tweaked to perfection though and was oozing culture (obviously) and money, which I used to keep good relations to my neighbor Wu (China), who apparently went for a domination victory. I was declared war upon twice by other civilizations (once by two civilizations teaming up against me), and both times used my good relations to have my enemies wiped out by China for me. I had to bribe my way through the last 20 or so turns, since Wu and I were the only civilizations left (~40+ cities vs. 2), and I was the only thing standing in the way of Chinese world domination.
![in b4 cultural win](https://i.stack.imgur.com/0c3FS.jpg)
Lots of interesting gameplay to be had in this game. :)
CIV5GameSpeeds.xml has all the information about what the different game speeds do. Adding up the number of turns for each speed gives us:
- Marathon = 1500 turns
- Epic = 750 turns
- Standard = 500 turns
- Quick = 330 turns
You can also disable time victory, in which case there is an unlimited number of turns. I'm not aware of a guide to all the advanced setup options. Most of them I think affect the random generation of the world. If you have questions about a specific one, feel free to create another question.
Best Answer
There are three possible reasons for this:
1) You are in revolt You didn't mention which (if any) expansions you're using - but in the past if your civ was in revolt, production and even worker ability would plummet to the point where they're basically useless.
Solution: Gain happiness and take your city out of revolt.
2) Worker Bug This bug still exists. If you place your worker on auto, often times they will do very buggy things - especially if you're a civ with custom tile improvements (ex: terrance farm). Sometimes they just run back and forth between two tiles, other times they take 2 turns to build a farm, then cancel it and take two turns to build a trading post - and they repeat this for hundreds of years.
Solution: Don't put your workers on auto. Or, if you really want to put them on auto - make sure they're doing their jobs!
3) Other Bug Despite Civ Vs popularity and many patches, there are still a number of bugs that occur.
Solution: The best thing you can do is try and do some self-troubleshooting. In your case, I would begin by checking the status of your worker each turn. By selecting the worker as he's making a farm, it will tell you how many turns remaining it will take to build the farm. Is that number changing each turn? Try to narrow down the problem, and maybe you can find a solution with the info you gather!