First of all welcome to the forum and back into tropical fish keeping.
First, there are several things which will need doing BEFORE any fish go near the tank.
Cycling the tank to create a colony of good bacteria used to break down waste. You can do this a number of ways, although I would highly recommend the fishless cycle for a number of reasons. 1), you dont potentially harm any fish as conditions in the tank are very toxic during this stage, 2) using a fish (alive) to cycle a tank means 1 of 3 things, you keep the fish and have to work out a stock around that fish, you kill the fish (cruel), you try and take it back.
You can read a well written article on cycling here
While the tank is cycling, you can work out a stock list, sadly though in a 30g tank you are very very limited in terms of what cichlids you can put in, I would always recommend at minimum a 40g breeder or ideally a 55g+ tank.
Reason is cichlids require space, not only for territory but also swimming. Smaller tanks offer neither unfortunately. Now this doesnt mean all cichlids are out the question, colorful ones sadly though are, they need a bigger tank due to aggression and ratio stocking levels, most African Rift lake cichlids need to be in groups of 5, 1 male to 4 females to spread aggression from a spawning male.
Before I offer any suggestions as to potential stock, one CRITICAL piece of information is needed from you....what are your water parameters from the tap/faucet.? Messing around trying to get the correct pH, hardness level is not easily done in a smaller tank. This information can be got from having a test kit, API master Freshwater with a separate kit for GH and KH, this will give you everything you will need to monitor the tank while it cycles so you can see the progress, in the future it will also allow you to see how well the tank is doing.
The other way to get this information is to take a sample for your tap/faucet to a local fish store, MAKE SURE they write the actual numbers down though, good, low are NOT acceptable in monitoring the tank.
I know this is a lot to take in but for the well being of both the fish and the success of the tank, they are needed.
Welcome again and look forward to getting this tank going with you