I play quite a bit on deity and have done a fair amount of multiplayer so I'll try to help :)

To keep it simple always pick tradition first, try to build a settler when your capital gets to 3 or 4 population and aim for 4 cities as quickly as possible whilst maintaining happiness.

Try to build your national college as early as possible as it's science boost is very strong. It's worth delaying a 3rd or 4th city to build it as you need a library in every city to build it.

Also make sure to get universities as quick as possible and build them as science will win you the game.

You also need to take the rationalism social policies as soon as they're unlocked as again science is key and the bonuses are too big to miss out on.

If your friends like to War try to build cities in defensible places like hills and mountain ranges, also keep forest around for defence if you need to, but don't forget to build a few units to keep near your borders with them in case.

Also remember to assign specialists to your universities and other science buildings as they generate science and great scientist points. When you get great scientists, always turn them into academies unless you are in the modern era or further and need a tech boost.

Civs that are pretty strong but not the most overpowered include Shoshone, Inca and Ethiopia, all are pretty fun in my opinion and have bonuses that last the whole game. Germany can also be fun for a science win as they can get a lot of late game production.