1. Do NOT do hood time with another pilot unless released to do so my your CFII.
2. Getting released to do hood time after "8 hours with a CFII to cover approaches" is not the way to learn instruments. The first 8+ hours of most instrument programs will be BI. As a matter of fact, you will spend most of your time on BI. BI is like the drills in sports and music. If you don't learn them correctly many bad habits will be formed that must be broken later.
3. Learn how to fly your airplane. Figure the power settings for different configurations and know them.
http://www.cfidarren.com/r-powerperf.htm
Be able to land on the center line every time.
Be able to land at the recommended approach speeds. I had one instrument student who did his landing at 90 knots... in a 172, zero flaps. He used up almost all of an 8500' runway. We had to spend the next few lessons on private pilot maneuvers and landings before we could continue with instruments.
3. Go into busy airspace and get comfortable communicating.
4. Go to faasafety.gov and take some of the free on line courses that will help you, such as IFR Regulations and the AOPA Pneumatic Systems course. Don't worry about the AOPA approach courses until you get to that point.
5. Does your airplane have a GPS/autopilot? Know how to use them... and I don't mean just the direct to function of the GPS.
6. Know the other systems on your airplane. I've had to spend instrument training time teaching pilots how to use their JPI engine monitor.
I'm sure I forgot some things and other instructors such as Ron and Bob will chime in.