Hardly anyone has the drive and the talent to be a top level player, but most freshman guitar majors have enough skills to make a living playing the guitar in classical guitar style. The skill level needed is to be able to play the 20 Sor Studies (Segovia Ed.) confidently. There are three of four of these studies, BTW, which will fit into a restaurant repertoire, then all you need is a bunch of tricks. These tricks will allow you to arrange popular tunes in an impressive manor. They will basically allow you to make the guitar sound like three instruments playing at once: melody, bass line and middle part/chord. This really impresses people. Go strong on popular melodies, light on the classical pieces (everyone likes Romanza). The styles I used are shown below.
1) Alternating bass and/or Root/chord, 5th /chord style (Merl Travis)
2) Waltz style (see Tarrega's Grand Waltz)
3) Habanera style (see La Paloma) I used a middle chord when arranged in this style.
4) Beguine Style
5) Bossa Nova Style (https://www.youtube.com/watch?v=0xTqNrWx4Xs
) steady Root/5th bass, syncopated melody and syncopated inner chord whenever possible.
6) Arpeggio style (Sor #15)
7) Tremolo: don't be afraid to overuse it if you got it.
I got inspired to write this from the "Playing a simple song" thread.