Listen back to your takes to be sure they sound the way you want them to sound. If you do a take and you know you can do better on the entire piece, re-record it. And bring back-up instruments, in case a guitar string breaks or a xylophone bar snaps. Arrive early to the studio to set up. These are big money-savers.
All record execs prefer CDs.
Almost all vehicles have CD players nowadays anyway. If you also want tapes, you can order those on the side, but the CDs are key to having people take you seriously. OK, so you'll make CDs. Hundreds, if you are serious about your potential career in music. So you need to find a company that can reproduce them and make them stand out in a sea of CDs.