One should always be learning something new. I recommend buying Mark Nelson's fingerpicking book and learning every piece in it, even if it takes five yrs to do so. Spend at least a half an hour each day and try to memorize pieces, one phrase at at time until the piece is completely memorized and until it can be played reasonably well. Then play whatever you bloody well want; your fingers and mind will be ready. Tony Mizen's From Lute to Uke is another beautiful set of pieces that will serve as exercises and paths to enlightenment.