I am a flight student preparing to practice stalls and stall recovery in a Tecnam P-2002. I have already done spin recovery. On top of that, what preparation techniques have others found useful?
You will impress your instructor most by being eager to learn and learning quickly, and by having done book work beforehand. Just do some reading on stalls and really get to know the 2002's Operating Manual, especially the numbers and limitations.
Be careful about trying to show that you already know it all. If a student has taken the time to learn the operating manual and knows all the important numbers and limitations by heart, and can recite emergency drills etc while under stress, the instructor will way more impressed than if a student tries to show they already know how to do the lesson. That being said, just read up, and really learn the manual.
First, the low-hanging fruit: has your instructor provided you any homework for the upcoming lesson? If so, have you done it?
I'm an instructor, and believe me, it's very easy to tell which students are doing their homework and which aren't. As John K says, doing the assigned work beforehand is a fantastic way to impress your instructor.
If there's no assigned work, you could ask for some. Unless your instructor is very new to the field, he or she probably has several resources besides the "standard" textbook that you could look at. I know here in the USA there's at minimum the FAA book, the Jeppesen book, and the Rod Machado book, and each one explains the same concept a little differently. A variety of views often helps with mastering a concept - if you don't understand a topic from one source, you might understand it with another.
Have you been chair flying? Learning numbers is good but flying is an active physical process. Find a quiet place, sit in a chair with your eyes closed, envision the cockpit, and then actually move your hands to the places that they would go during the maneuver. Taking five minutes to remember how to do it on the ground (for free) is much better than taking five minutes to remember how to do it in the air.
Are you training alone or are there others in your class? One of the best ways to learn something is to try to teach it to others. If you have classmates, try to arrange a small study group that meets regularly. Each person chooses a topic and then does their best to explain it to the group. I will warn you, it's very hard to get a group of people to agree to this, at least around here.
Two great answers already, but I’d like to add that besides doing your homework be there on time and listen to your instructor! S/he will be telling you what you need to do.
Not many more frustrating things for an instructor than a student who is so eager to please/show off that they don’t listen to the instructions.