Between Two Cities is a game where players build two separate cities, one with each of their neighbors, and whichever one scores lower is your score. This means that doing nothing for one city and everything for the other is not a viable strategy.
The game is 3 to 7 players, so you can easily play with all of your family and friends. Because of how the game is played (each person adds one tile to each of their cities every turn), it is very social and requires good teamwork with other players to score the most points possible.
In my experience the best way to win the game is to put a roughly equal effort into each city, and to utilize taverns.
Taverns scale slowly to start, but then really well once you get at least three of them. All of your cities should have at least one complete set of taverns. Parks don’t scale well but that’s in your benefit. Usually you’ll want to place just two park tiles and then stop. If you’re desperate for points then you should create a separate set of two parks. Factories score well, but you run the risk of people having more of them than you. If you have very few of each tile (not enough to score a lot of points), then you want to invest in houses. Houses can be worth up to 5 points each, which is a highest amount per tile.
Remember to work with your neighbors to get the right tiles into your cities. The people who do the worst are always the people who don’t work with their neighbors, because it leaves their city with no logical layout. Good luck!