How many tetras in 50 G

Question
I recently bought a 50 gallon aquarium and planning to keep only tetras. About 70-80% neon & cardinal and, maybe, a few other varieties.
Can u suggest an appropriate number (and combination)  I can keep ? <the more the better :) >
*by 'combination' I mean the other types that will look good with neon/cardinal.

I was also thinking about cherry barbs.. Are they compatible with these tetras ?
Lastly, what are the equipments I should get and steps to follow to ensure the fishes do well in my tank ? <presently I have air pump, internal power filter with flow rate 264 gallons/hr>

Answer
Tetra's and barbs are not a good combination, the barbs are much more aggressive than tetra's. Being tetra's are smaller you can used the one inch of adult size fish per gallon and you should not have any trouble at all. With tetra's you will want to keep more community/non aggressive fish with them. Otherwise your school will slowly get smaller.