Amateur rocketry, a.k.a. experimental rocketry, is an exciting, fun, and possibly hazardous hobby or occupation.  In amateur rocketry, specialized motors, higher-powered motors, metal airframes, and various other "less than predictable" materials are utilized, often in the attempt to launch a rocket of unheard of size, or to launch a rocket to an unheard of altitude.  Below, you will find a collection of information on this topic, some of it from our own experiences and some of it from the experiences of others.  All of the information should be of help if you decide to follow this venue of rocketry.
Fly high. 
Fly safe.

Chris Comments on Safety
When dealing with amateur rockets, the most important thing to remember is safety first.  I know this sounds cliché, but I've definitely had more than my share of close calls with amateur rockets, most caused by mistakes I made while manufacturing the propellant grains or when I was packing the recovery system.  If possible, you should let someone else examine your rocket after you've prepped it, just so he or she can ask questions about  it that may, if nothing else, bring your attention to an oversight that you made while preparing your bird for flight.  Another thing that may help is the digging of a bunker if you are testing an untested experimental motor, especially of your own design.  Now, I wish that I had taken the time to dig bunkers for my own non-static motor tests.  It would have saved me a great deal of aggravation after each flight.

We got this tidbit from the ROL Forums, and found it good advice:

"... prefer the Graphite nozzles and cases like the AMW/Kosdon stuff. The biggest differences are : Graphite does not degrade or disintegrate [sic] like Phenolic when the motor burns. Graphite will give you a different ability to make what I believe is a better motor because of this. You can get a lot more uses out of a Graphite nozzle as opposed to a Phenolic. Phenolic for the most part is a single use and toss it. With Graphite you can get between 10 to 30 flights out of 1 nozzle.  Phenolic nozzle motors seem to be very regressive vs. Graphite being Progressive burning. The all around benefits for Graphite are much better. As far as where to get them, try Purple Woody and Loki Research. (ed. note: Aerocon stocks them as well.) The cool thing about getting ones from them is that they can make you one in about any sizes 38 mm to as big as 5 and 6".As well as they come tapered for inlet and outlet cones and divergences. Also made so you can drill your center hole or have them do it. Cost $ 20 and up. I use them in Kosdon cases and AMW cases. You can (if the size is right) use the Kosdon and AMW ones as well.  As far as the CP tech. Plasticizer, I got it and I plan on using it. Why? Because then you can reduce the amount of binder and/or increase the Magnesium content and hopefully get a more dense mix.  A denser mix is better as well as it will give you a much better C* and can enhance the performance characteristics of the propellant. The other reason to use it is that it can and will thin the mix making it easier to mix and pack into casting tubes.  As far as liners the liners I like are the ones I get from Missile Works. The Paper/Phenolic ones work great. Besides the fact that Jim Amos has lots of great products and is very knowledgeable about this stuff.  They can be used for either AN or AP loads or really any propellant you wish. Do you plan on segmented motor design or long single grain motor? The segmented or "Bates grain motor" is a higher performance then a standard core burner. That is due to available surface area.  Each design has its place. If you are Going to be doing a Standard Core burn motor then you will need a mandrel (a rod) with wax paper coated in Dow 111 grease and after the cure you will need to remove the mandrel and then sand or remove the outer surface of the core hole to get rid of the wax paper and grease. In a bates grain you can use a coring rod but for most purposes it is easier to drill to the correct size. Plus you can use the shavings for many things (e.g. Burn tests or igniters, etc.) My total recommendations are to Get the CP tech book and software from John and read it!  Use the software as well. It even comes with a great video. I also recommend to get Terry McCreary's book as well. Do the same with it. If you get the chance Talk to guys like Mr. McCreary and John Wickman and Jim Amos and others that are the Experts in the field. Be sure to take good notes. See if you have a group or organization that does EX locally in your neck of the woods. Try not to go to fast. Take your time and really learn all that you can before going to each next level of EX. from learning books and software to casting and propellant testing of samples in non cased environments and as well as to strand tests and static tests and etc. I know of people that have done EX for 2 years now and have not even flown a motor that they have built in a rocket yet. Asking questions is very important."