I'm not a ram expert or even a tropical fish expert by any stretch, but I've managed to keep my GBRs alive for six months and counting. I have a breeding pair in a South American community tank, with Cardinals, Black Neons, Rummys, and Sterbai Cory. Tank is pH 6.7-6.8, soft water (2.5 dGH), and the temp is 82 F. There are many things to consider...
(1) As mentioned, a mature tank is needed. Most say it should be cycled and stocked with something for at least 6 months. I added my rams after 4 months and they had no problems. I wouldn't suggested adding earlier than that.
(2) Stock quality is probably the most important thing. Don't get them at the local fish store, as many are inbred/pumped up on hormones and possibly diseased as well. Buy from a reputable breeder instead. I got mine from Yunite (germanbluerams.com). If you get them directly from a trustworthy breeder, you can skip the added stress of temporarily housing them in a quarantine tank. Avoid the specialized forms (Gold, Electric Blue, Balloon, etc.), as their genes are less diverse. German Blues and wild-types are the hardiest.
(3) Tank water should be 80-86 F (82-84 is optimal). Cooler water will compromise their immune systems. Nitrate should be as low as reasonably possible (I keep mine under 15 ppm). I've found that Hornwort reduces the nitrate in my tank by about 5 ppm per week. If you have hard water, you'll need to cut it with RO water. I don't know if they're super-fussy about pH, but I imagine that it should be lower than 8. Water hardness and temperature are more important.
(4) Related to (3), the water needs to be very clean. Not super-pristine like discus tanks, but still very clean. That means ~30-50% water changes per week. I do 2 x 20% water changes every week (which is equivalent to one 36% change).
(5) Tank should have dim lighting, with plenty of hiding places. Based on my experience, they get more skittish as they get older. They like plants and especially caves.
(6) Do not stock two males in the same tank, and do not stock other cichlid species unless you have a really large tank. (Actually, two males may be OK if there are no females present, but I wouldn't recommend any more than one male and one female in a small/medium tank.)
Brookster and coralbandit can add anything I've forgotten. They're somewhat demanding, but I agree that they're worth trying if you're willing to put in the effort.