the best tip is to learn all the technique 'standard' pieces.
Barrios's concert study
Tarrega's recuerdos del alhambra.
any entire bach cello/lute suite bar cello suite no1 (just not diffficult enough)
Villa lobos study no 1, 2 and 11.
Brouwers Decameron negro (all three movements not just the first)
Turina's hommage to tarrega (particularly garrotin).
once youve mastered these,
then move on to the complete works of Villa lobos (in particular the suite populaire braziliene and choros no 1) and Barrios (La catedral and walz no4 op
and start to try some of paco de lucia's compositions.
(every classical guitarist should try to attain a flamenco players level of technical proficiency)
that should keep you busy for sevral years!