With a 10g tank, your options for adding fish are pretty much limited because of the smaller size. If you are keeping basic tropicals, the general rule is one inch of fish (when fully grown) per gallon. That is not a hard, fast rule, but something to think about in general. You wouldn't want to put a fish 10 inches long in a 10 gallon tank, so know how big your fish will get to be when fully grown before you buy.
You also have to consider if you are planning on shrimp or anything like that which adds to the bio load. If you want goldfish, well, I wouldn't put them in this tank.
In order to give you better advise could you let us know a few things?
How many cherry barbs are in the tank now?
Are you keeping them or are they 'loaners'?
What kind of lights do you have?
Are you willing or able to upgrade the lights based on plant needs since some plants require more light than others?
What are you using for substrate?
Honestly though, (IMHO
) a small tank like this looks better with plants and just 1 fish in the 3-4 inch range (like a betta, dwarf gourami or medium sized angel) or 3-4 small fish the size of neons. The fish have more freedom to move around plus you can add a snail or a few decent-sized shrimp (large enough not to become dinner) without overcrowding or overloading the tank.