Any advertisement can be as detailed or generic as you need it to be. You must have a clear idea as to who you want in your band, this is the most important factor, whether it be a bass player, singer or drummer etc. Ask yourself : What qualifications and experience are you looking for ? Does age matter ? Make a list of questions and keep it by your phone, then you can interview anyone who phones you straightaway. Questions you ask should be such that can get short responses or even just 'yes ' or 'no' answers. You can take notes faster that way. If someone seems a likely candidate take their phone number and tell them that you will call them when the interviews have finished, always try to get back to people within 2 to 4 weeks if possible. Look at your notes and decide who you want to call, organize a time suitable for everyone you want to call and most importantly make the meeting where you choose. This is a crucial part of establishing yourself as the originator of the band and on being the main influence of the direction you want the band to go in.
A word of caution though, it may not be a wise idea to invite them to your home at least until you know them a little better but it is of course your decision, bear in mind though that you are all strangers at the outset.
Take it slowly and informally on the first meeting. Make introductions, share experiences, set goals, discuss plans etc. Doing this will give you insight as to whether each person will be able to work together and gel well. People who think they know everything for example, will just create problems for the others. Be realistic but fair in your judgements, if someone is clearly not right for the band it is better to reject them immediately. otherwise in time they will damage or spoil the whole band. Your second meeting can be a "jam" session. At this time you will be able to gauge whether everyone will get on together or not but do not be too quick in deciding.
I remember auditioning for a band that I had known for some years and I always wanted to be part of it. I was so self conscious that I could not relax and everything seemed to go wrong. My experience that I had gained previously when performing solo did not help me either. I was sure that they would not want me but to my surprisBe, they did ! The second audition was no better but evenso they gave me yet another chance . On the third edition it was so different, our voices and music blended so well that I knew I would be in their band. I shared this story so that it may encourage you to give your new band some time to get used to each other and to become confident together. However, if you find that over a period of time nothing seems to work you may need to reconsider whether the band is right or not but of course, you alone can decide.
There is not much more to say. Once your band members are decided on, you are ready to begin. Share any original tunes with others and find out if anyone else has written material themselves. Be real and open for anything. If you know your own priorities from the beginning it will keep you focused through the good and bad times that you may encounter. Always remember : "Nothing ventured nothing gained"