How do novice cichlid keepers choose what cichlids they want to keep? Everyone has a different reason for why they chose a species or multiple species to keep. Sometimes the choice was heavily influenced by pragmatics (e.g., the size of tank, the type of source tank water). In other words, the size of the aquarium home determined the most appropriate species. Sometimes the choice was solely driven by personal preference (e.g., typical temperament of the species, species appearance). In other words, the decision was made based on what the cichlid looked like or how it behaved at the store.
There is really no "proper" way to choose your first cichlid. However, there are a few things you should consider before making the decision, and I've listed them below:
If purchasing just one and you want something with a lot of color, consider purchasing a male. They tend to be the most colorful in adulthood. If you purchase a juvenile cichlid, it may be difficult to determine the sex because most species that are sexually dimorphic in color aren't distinguishable until adulthood. If you plan to purchase several and they're all juveniles, know how big they'll get and know how aggressive they tend to be, especially if they're all the same species. If you get several of the same species, you'll most likely end up with at least one of each gender. Do you have a plan if a pair is formed and they spawn? What will you do with the fry, assuming they survive?
The most appropriate way to figure out what to keep is answer the questions above and do some homework by reading about cichlid keeping. What you want to keep and what you should keep probably won't be mutually inclusive. Go with the latter until you get some experience. Ultimately, what you should keep will reveal itself when you answer the questions and do your research.
The Cichlid Room Companion
Tropical Fish Hobbyist
American Cichlid Assoc.
African Cichlid Hub