Recording is very different than playing live.  When playing live, it's very easy to turn up the volume if you need more.  When you run out of room to turn things up, you just get bigger equipment or a bigger room.

Recording has some limitations to deal with.  A recording can only hold so much data.  If you fill the sound spectrum with one instrument, it doesn't allow enough room for anything else, the mix gets muddy and you cannot differentiate between the individual parts.  What you have to do is remove unneeded frequencies from one track to make room for another.  For example, cut the lows on the electric guitar to make room for the bass.  Cutting the low frequencies is usually required on most of the rhythm instruments, more so than when playing live.  I included this here just to forewarn you.  As a musician, I understand that we have a hard time when someone starts trying to adjust our sound.  Especially on our rigs.  The EQ process will make the difference between sounding like a garage band and the recording you want.  The first step in the EQ process is to make sure the source sounds right for the mix.  It is much easier to record something right the first time then it is to try and fix it later.  Keep this in mind when preparing your equipment list and sounds.

The obvious thing to do when preparing for the studio is to practice the songs you want to record.  If applicable, practice as a group but also practice on your own.  Try to know the songs well enough that you can play your part by yourself; counting and knowing where to come in.  I suggest you also practice with a click track not just the drummer, this will make recording much easier.  Also when you play live you can get away with little mistakes that no one ever notices, but if you record these little mistakes they will stick out like soar thumbs and haunt you for the rest of your life. 

When you practice, make sure not to move at the end of your part.  This way when you record, you have practiced the habit of creating a measure or two of perfect silence.  There is nothing worse than recording the perfect drum track, only to have the drummer set his sticks down during the ring out of the cymbals.

We are human, nothing we do will ever be perfect but we should strive for excellence.  When you are recording you will make mistakes.  Don't stress out about them but please point them out so that we can fix it.  If you freak out about messing up it will just make you more nervous.  Don't even apologize for it; feeling bad about mistakes just increases the pressure to play correctly.  Everyone is nervous in the studio, you are stuck in a strange environment with people watching and your trying to do the best performance of your life.  The more you can relax the better off you will be.  Take some time, lay the track down a few times, take a break, and if need be just play until you are comfortable.

Most importantly is prayer.  Make sure to pray for unity, effectiveness of the product, protection of the recording process/human interaction, and for wisdom to make your creation the best it can be.