How much power can your engine handle? Most nitrous kits offer different power levels, so you can choose the one that best suits your needs. Choosing a nitrous kit based on power level depends on your driving needs. You should be fine with the average kits, but a bigger pack may come in handy if you plan on off-road hill climbs. The ECU on your Bronco should also be tunable, as it can impede the performance of the nitrous kits if it's not tuned properly.
Dry, wet, or direct port systems are available; which do you prefer? Generally, the first two systems are cheaper and easier to install. On the other hand, the direct port systems will give you more power but will cost more and take more time to install. Be sure to seek professional help to install any of these systems.
After you've installed your nitrous kit, it's time to hit the open road and enjoy the extra power! Drive safely, and don't break any road rules!