The finger pad will always likely produce a dull tone. The important thing is to be able to control the tone and reliably reproduce the same sound, tone and volume, each time you attack. I use a technique where I touch the edge of my finger pad to the string and let the string glide off the pad, onto the nail and then launch off the nail like a slide (I may not be describing this very well). I also push the string in towards the top a little (this produces a very loud free stroke sound). But I play classical rather than steel string acoustic. I have used finger picking techniques on electric but I use my classical approach there as well.
I would recommend taking the time to explore the attack, angle, pressure, and other variables on the open strings. This is what it takes to develop good tone on classical. Once you get the sound just right try to remember what you are dong and drill it over and over. Once you can play a finger picking sequence on the open strings then start applying it to chords. If you lose the tone it may not be your right hand but a lack of coordination with the left (e.g. releasing the left hand fingers too soon and making a dead sound).
As for placement it is true that in the beginner most technique books way place (i, m, a) on the (G, B, E) strings, and use the thumb for the three bass strings. But that is not set on stone. Many finger pickers use the fingers on the bass and thumb the treble on occasion, it really depends on the sequence of notes and what is easy to grad, play smoothly, and produce a good tone.