Once you understand a bit about how soccer is played and broadcast, it is a very easy game to follow. Each team's colors are displayed on the screen. By watching which way players are moving and knowing the colors of their goal keepers' uniforms, you can easily track the action and see who is winning.
For soccer fans there should not be a problem in keeping up with the sport. Fans outside of soccer can merely just look it up on the Internet or capture the highlights in some form or fashion. In this day and age if you want to know about something it is at the tip of your fingers.
Soccer is a national past time of many European countries. Soccer is a part of many cultures and it is very useful to keep up with it. It is very similar to keep up with as with any other sport. There are a few key teams depending on the region you're talking about, and a number of key players. How far into detail you have to research depends on passionate you are as a fan.
Soccer is a sport that is not as widely celebrated in my country. Other sports are easier to follow due to the ever-expanding fan base, which includes commercials, merchandise, etc. What I have witnessed, while watching soccer in a group, people tend to lose focus on the game (possibly due to their lack of knowledge about the sport in general), and turn their attention to their family or friends. With larger sports (football for example), people tune in and stay engrossed in the games, because our society promotes that.