Before embarking on a full recording session, every song should be demoed and approved by all parties involved in the project. There's no point going into the studio with half-written songs or songs that some participants don't think will work. Demoing and "living with" songs for a while help the artists select the material they like best and consider which elements are crucial to making it work. All arrangements, solos, lyrics and vocal harmonies should be composed in advance. If you're efficient in the studio and find yourself with time to spare, you may be able to try a few additional ideas, but don't leave yourself floundering around for ideas when the clock is ticking. In any case, be extremely careful when adding unprepared elements to your song. A new idea that sounds great after a long day in the studio may not make as much sense on the finished record a week later.
All musicians should be fully ready to perform their parts, and the group needs to have spent plenty of time practicing. This means that all group members will fully understand the material and be happy with it. This will lessen the chance of having to eat up valuable studio time by running through take after take to get it right. Factor in a period of rehearsal time when timetabling your recording session.
All your equipment should be fully serviced; for example, guitars should be restrung and set up before the session. Go into the studio with plenty of spare parts; again, using guitarists as an example, you will need spare jack-to-jack leads, 9V batteries for any effects pedals, plectrums and strings. If you have something that could go wrong, pack a spare if possible. Also, be in touch with the studio and get a full check on which instruments and amplifiers it has on site. It may have equipment you want to use, but conversely, you might need or want to take your own equipment.
If you find yourself with a finished music product but nothing to package it in, you're looking at a delay before you can release it. The artwork needs to have been taken care of in advance so as soon as the record is done, it can go to press. Remember, also, that the cost of packaging copies of your record for distribution must be factored into your project's budget.