From a buddy of mine still the best list Ive seen) Do it yourself! Dont trust anyone else to take as much care as you will.
2) Make sure your fuel system is up to par. Dont rely on any stock fuel pump. Either add a bigger in-tank pump or big in-line but not both.
3) Install a fuel pressure safety switch.
4) Install an rpm window switch.
5) Install a WOT switch
6) Either retard timing or use race fuel.
7) NEVER hit it manually. Let the window switch and WOT switch do it for you.
Dont use it below 3000rpm.
9) Make sure you have colder plugs with copper electrodes.
10) Take ALL your plugs out every once in a while and check them.
11) Get a good bottle heater and never use propane torches.
12) Make sure everything is wired through the ignition circuit.
13) Tune your motor for best results BEFORE using N2O.
14) Get a good capacitative discharge ignition with a soft rev limiter. DO NOT EVER rely on the stock limiter which cuts the fuel off.
15) Make sure you have a good N2O filter.
17) Start with a small shot when youre testing.
1 Test your system often. On a wet system a completely simple way is to hit the juice while the bottles closed. You should dump a load of fuel in and the engine should bog. If it doesnt - that fuel solenoid isnt working - bad news! Thats not a complete test but it tests some critical pieces of your system.

If you do all of the above the odds are pretty good your system and your motor will last a long time.

Also make sure the bottle is bolted to the floor or something.

Chris