+1 to practice.
Its been a while since I've been in a honest-to-god, well set up studio but I've always found these things helpful:
Don't use the studio time to write. Its ok to do this if you have a lot of money to spend, but if finances are a concern make sure everyone knows exactly wheat they want to accomplish before they set foot inside. This includes individual parts (obviously) and what types of effects you want to use.
Make some sample recordings before you go in. Try to get the sound as close as possible to what you want the finished product to sound. If you're relatively new to trying to communicate with an engineer it can be much faster and easier to have an example of what you're trying to achieve than using language and descriptions he may or may not understand.
Make sure the equipment you bring with you is high quality. I've seen many people waist a lot of time trying to get a crappy guitar or bass to sound good. It can be done, but its hard to do and generally not worth the trouble. If this means you have to borrow an instrument or two from someone else, that's fine. Just make sure you have it long enough to gain familiarity with it before you try using it in the studio.
Don't bring an entourage with you to the studio. The members of the band should have already worked out what they wanted to accomplish individually and collectively with the studio time. Maybe bring one guy you trust with you to give you another perspective if problems arise. Other than that, avoid having the whole band there all the time and especially avoid bringing outsiders (girlfriends, friends) with you. It will undoubtedly lead to a lack of focus in the session and general time waisting.
+1 all of the above.
When you have everything done in the preproduction phase of your recording process make sure that you can do it in your sleep. 6hours a day might seem extreme...but if you can hang it out there that long then you will do fine in the studio.
I know that this sounds nuts but ... you can not rely on any cues. NONE!!! no vox, guitars, keys, NONE. If you can do it without any cues you will be fine.
When we went in the producer alloted 48 hours for each instrument, for 10 songs. That doesn't seem like a lot of time, or to others it seems like forever. But ... we beat the odds and the time for each instrument grouping as we had worked about 3 hours a day during the workweek and 8 to 10 hours on the non workweek for about a month and a half before going into the studio.
When I got there several things had changed and I had to make adjustments on the fly. The drummer and guitarist went first and had their parts in the can. The vocalist went next and got most of his stuff in the can. When I got there there were changes, as I said, to 3 or four of the songs. With warming up (string changes, etc.), playing through to the point of changes in the song (not chord changes), making the changes in my mind/fingers, and finishing the songs I was in there only 3 hours. I had my parts down perfect, as much as I could, and actually pulled a couple with only one take.
The producer commented on this fact...we were prepared...and actually used colorful metaphors for "that was perfect" on several of my cuts.
Why was that? Because we had a new approach to the recording process. Work, rework, work, work, practice at home, work, rework, finalize, practice, practice, practice, practice, practice, practice, and then finally....practice to be very sure.
This also helps with your live show. You know the music so all that is left are the cuts between and how you are going to interact with the folks that pay your salary (audience).
Just My Thoughts.