I think:
a) You should specialize in guitar or bass. If you do both you risk being perceived as a mediocre player.
maybe, but i would rather leave opportunity open for both
b) specify what style of music you want. Otherwise you will attract too many people with such diverse musical interests it will be hard to get commitment.
Im open to pretty much anything so long as I get to use some chops and have fun. Im not looking to hire anybody
c) Specify the kind of person you want. It's not only about the music. If you don't want to be run off your feet getting gigs and being a band manager, indicate players should be willing to share equally in the work of getting gigs. This will reduce the response rate dramatically, but you will get people who will do more than sit back and complain at you about gigs.
I have absolutely no idea how to get a gig thats why im mostly interested in joining an established band not do a start up project
d) indicate what the pay is expected to be. Indicate the goals for the band. Make money? Creative outlet? Just for fun?
I drive an hour to play in a church band for free, id like to get paid but it doesnt realy matter. I just want to gig.
e) describe personal characteristics. Do you want people with "good values"? The values of the people in the group have a big impact on the cohesion in the group.
Im not sure an ad will rule out the type of behavior I want to avoid (unless I come across as judgmental)
I think the ad misses really -- you'll get a broad group of people, will invest time in trying to get a repertoire and then people will quit when the band doesn't meet their expectations.
The last thing you want (if you are like me) are what I call employees. Guys who will come to rehearsal, gripe about pay and lack of gigs, but refuse to lift a finger to help. But that's just me. Decide what your non-negotiables are, and put them in the ad.