I agree. First the big question is African or SouthAmerican (aka New World) cichlids. You can't keep both together because they have very different water requirements. Technically you could by keeping the water in the middle.... but the fish won't be as happy and it will show in their behavior and lack of those notoriously flashy colors.
Also keep in mind their eventual size. You can buy German blue rams and electric yellows from the same store with both being 2"... but in a few years, your electric would be twice the size... and twice as aggressive!!!
I'm beginning in the world of cichlids myself and one thought is ringing true....
YOU HAVE TO DO THE FOOTWORK.
Research research research. Because if you set up a good tank formula before you stock your tank, you've won half the battle. Ask advice from these fine folks here. Ask others. Read books (recent ones... nothing outdated). Know what you're getting and what it will come to be in the future. Prepare for that. Yeah, it sounds like a lot of hassle, but if you do it now, the actual fishkeeping will be a cinch. You'll know exactly what to expect of your fish, you'll have a beautiful, well crafted environment that is both eye-catching and pleasing for your cichs, and you'll lose less in the costs of fish replacements or treatments. In short, the work now will pay off a lot throughout the ownership of your cichlid setup.