There's not the right way to do it...
How you should level your feeders should depend on your 1*/2*/3* cards distribution. But in general:
1* should NEVER be fed directly to the card that you want to level, they should be used to level the 2*/3* feeders that you want to ultimately feed to the card that you want to level.
2* feeders can be level to lvl 4 with 3 x f1*, lvl 5 with 5 x f1*, lvl 6 with 6 x f1* (note: you must have lvl 10 blessing of Valkyrie and 2 of the f1* must be the same type as the feeder you are leveling), or lvl 10 with 16-18 x f1* (depending on type of the 1* and level of blessing of Valkyrie)
3* feeders normally are leveled to lvl 10/11. There are couple of ways to do it: either with 16-18 x f1*; 5 x f2* + 1 f1*; 2 x lvl 4 2* + 1 x f2* + 1 x f1*, etc.
Those leveled 2* and 3* feeders can then be fed to the card you want to level, ideally all at once to minimize the luna cost (i.e luna cost is related to level of the card you are leveling). Some people even bank all the card before trying to enhance to get the most of out it.
Hopefully this will answer your question