Here we go!
1. Choose starting stats that give good HRT and CHA. You may want to take a few security or driving points too.
2. Recruit 5 hippies (find them at Vegan Co-op) with good HRT, CHA and utility skills you need/want. If you didn't take security or driving for your founder, your hippies will need to have them. Note that since music is easy to train, you don't need it that much initially.
3. Raise money (donations, brownies, whatever, just don't risk your founder) so you have 1200 $.
4. Equip your squad with guitars and play street music until your squad's music skill is about 12-14, you may keep training further if you want to and if the hippies' heart doesn't limit it further. Note that training music won't be easy once your guys have a criminal record. You'll get some good money here, too. You might consider buying or stealing a car here.
5. You'll still need juice to be able to get sleepers, and guitar playing gives none. Raid the regular factories - they are safe because they have no properly armed enemies or speaker conservatives. Wreck machinery and run away as soon as you're spotted (or before!).
Now you have a guitar squad that should work pretty well. A few more tips if you're clueless about using it (spoilered in case you just wanted to get started)...
6. Recruit powerful conservatives as sleepers. The latte stand often has some, and the park is a safe place to find them although you may need to walk around a lot to find them. Alternatively, go to their nests: Court house for hanging judges, genetics/cosmetics for eminent bastards, and corporate HQ or CEO residence for CEOs. Of course, Cable Anchors and AM Radio Personalities are priceless too. You should also consider recruiting a policeman to warn about police raids (provided you're going to do something that raises heat - treason, terrorism and prison break are the ones available for a pure guitar squad).
7. DO NOT ATTACK THE CCS WITH GUITARS. You simply won't be able to stop them with guitars. Instead, don't anger them, just let them practise their art of violence... and the people will begin to hate them.
8. Cable/AM raiding is a very suitable thing for a guitar squad to do.
9. Money making is handled by your squad's street music initially, but later on you may either want to hire programmers to credit card fraud you some chaching, people devoted to collecting donations or just have a 100% Conservative CEO embezzle 10000$ a month. Not that you'd need much money, since with guitar squads you can easily avoid heat and thus can stay in the shelter.
Hope this helps!