I've only been in a recording studio once.. but I'd say the biggest thing is to have everything worked out down to the last decimal place. Particularly things that would otherwise be done as improvisation when playing live, such as the guitar solos and other instruments' solos. Every time you do another take, you are wasting money. Each band member needs to be able to play their own parts separately, with accuracy, each and every time.

You also might want to plan whether you are going to try and play it all "live" or play each track separately or some combination of this. By live, I mean that all the instruments play at the same time, just like if you were playing live. You record the entire track in one go. The other method is to record one track first, may be with the help of other instruments to accompany that person. So let's say you want to get the drum track down first.. then you might need for the rhythm player playing to help the drummer keep to the song structure or whatever.