Watch the Right Hand Fingers & Approach online guitar lesson by Diego Figueiredo from Brazilian Jazz Guitarra
When playing, I keep my right hand very compact and close together. This allows me to play very soft and fast, but still allowing me to play strongly when needed. We call this the "classical technique", and you can see my nails that I use to play in this style and get the sound I'm looking for. If you don't have long nails, you can use acrylic nails or try with just your fingers.