From our guild's website...
When you reach 50 you can either level an alternative character, or you can participate in the end game. Of course there's no reason why you can't do both!
If you want to participate in the end game, the most important thing you must do is start running the hard level instances. There are two reasons to do this. First, and most important, it will help you gear up for the operations (the eight man instances). Second, and closely related to the first, if you use the group finder once a day you can earn black hole commendations which help you gear up with black hole gear. This gear is the second best gear in the game.
The second most important thing to do when you reach 50 is to earn credits to fund your activities. The primary way you do this is to run daily missions. These are missions you can run once a day. Some of them pay as high as 16k credits! You will find these missions on Ilum, the Black Hole, and Belsavis.
Another way to earn credits is to do the daily space missions. These don't pay as well as the dailies, but hey, a credit is a credit.
Another way you can earn credits is to run heroics. These can be run once a day as well.
At 50 you have a choice to make. You can stay with the guild as a teacher, or you can be placed in a raiding guild (allowing you to run operations). The guild will not run operations so if you want to participate in that part of the end game you will need to be a part of a raiding guild.
There are two kinds of raiding guilds. The first kind is the hard core raiding guilds. These usually raid three or four times a week and require you to attend them all. The second kind is a casual raiding guild. These may also run three or four times a week, but attendance is not required.
Whether you stay or not, another important end game activity is to help other players. Social interaction is an important part of an MMO (Massive Multilayer Game). You can help others level, run heroics, and gear up for operations by running instances with them. You can also just be available for answering questions leveling characters ask.
Another important aspect of the end game at 50 is crafting. You can make a lot of credits on the GTN by selling your crafted items. You can also help people in the guild by making items for them.
Something else you can do at 50 is to search for all the datacroms in the game. If you didn't get them as you leveled, this can be very satisfying. The datacroms increase your base stats and make you a better character. BW has made finding the datacroms challenging and fun. To find out where the datacroms are and to get some help in finding them go to this site: http://www.swtor-spy.com/datacrons/
Finally, when you reach 50 you can pvp. I know, you don't think you're any good at it; but, the only way to get better is to do it. PVP requires special gear so will want to buy the recruit set first (about 130k), and then earn the next two tiers by pvping.
Life after 50 is good! Enjoy it!