Ive said this before and i'll say it again, I advise anyone to pick up Albert Lee's' Star Licks' vid where he goes through 'Country Boy', praps the classic chickin pickin track of all time. He uses a pick between thumb and forefinger and picks with the others.
Other top fingerpicking stylists are Chet Atkins, Jerry Reed, the Hellecasters, Leo Kottke, Mark Knopfler and Tommy Emmanuel. Some of these guys use thumb picks but I find them to rigid, preferring to use my thumbnail in a classical style.
Keep this quiet, but i ..ahem...use the wife's clear nail varnish to keep my nails tough. you may prefer salmon pink, purple..that's your choice. you dont wanna let your nails get too long so that you start to resemble some kind of mad witch. about 2mm should do it.