@HVS5b Awesome guide. I started reading some of the important parts. Very comprehensive. Thanks.
@Dushku Thanks for the detailed write-up. I watched your happiness management video and learned quite a lot. I'm currently playing a very successful match on Prince. I'm currently the most powerful civ with a large army and a massive science lead.
Well if you're having trouble keeping up with science; there are a lot of things you can do. I know this because I play on Emperor where the AI techs much faster.
One of the key components to Science is growth. So make sure you research Pottery for granaries and The Wheel for water mills. If you want your cities to grow fast, you should place them on a river.
Having an Aqueduct is also a must for growth. You can get aqueducts by either completing the tradition tree or researching Engineering.
The National College will help early science. You can build it after you research Philosophy. However, the National College can only be built once you have a library in each city.
Once you research Education and build universities; make sure all your Science specialists slots are being worked. Science specialists will eventually spawn Great Scientists; which can help you get through techs.
Something else that will also help greatly is to adopt the Rationalism tree once you reach the Renaissance Era.
You can also sign Research Agreements with civilizations that you have made a DoF with.
As for happiness, there are many ways you can deal with this. Once you search Construction, you can build Colosseums which will give you extra happiness. If you adopt Tradition, you can get the Monarchy policy which will give you extra happiness. If you go Liberty, the Meritocracy will give you extra happiness for every trade route.
If you're playing G&K or BNW you can also get happiness from religion. The founder belief Ceremonial Burial will give you +1 happiness for every 2 citizens following your religion.
If you're struggling with gold, the "Monarchy" policy from Tradition will give you extra gold. Also the founder belief "Church Property" will give you extra gold for every city following your religion. Building Markets once you research Currency and connecting cities with roads will also help with money. In BNW, you can use caravans to establish trade routes which will help gold. And lastly, you can adopt the commerce policy; which will help with gold.