There are people on here with much more experience than me at this. However, this is how i feed mine and it seems to work well.
10 fish 6-9 CM/ 2.5-3.5 inches I feed them 4 times a day. Once as soon as i wake up, once at about 11:00AM, once at about 4:00PM and once right before bed. I feed the high protein foods at the beginning and end of the day. So beefheart in the AM/FDBW in the evening, during the day i'll feed flakes once/pellets once. As to the exact amount of each it varies. I'll put in a small amount first, if they eat that like oinkers in 2 seconds, i'll add more BH or FDBW. in the morning or night. For the NLS pellets i feed, it is about 1.5 pellets per fish. So i have a little measuring spoon that i believe is 1/2 tsp or maybe 1/3 (i'll have to look when i get home) but it holds about 20 1mm pellets, I'll feed that. For flakes, i usually feed a small pinch I do not have an "exact amount." I always feed them very little flake as it tends to dirty the water and go in the prefilter very easily. I would guess it is less than 1/2 a tsp.
Larger fish, i feed 3 times a day, morning mid day and night. Their diet is also "mixed." I feed FDBW, Live Blackworm/whiteworm/bloodworm, Beefheart/Seafood mixes, New Life Spectrum flakes/pellets, spirulina flakes, nori and sometimes mysis shrimp.
The trick to feeding is to observe your fish. Feeding "just the right amount" is not an exact science unfortunately. One day you'll notice they'll eat everything you put in, the next they will eat 1/3 of that amount. I always start small, just not so small it creates a war for food. You can add food to your tank, you can't take it out as easily.