Important note: It is impossible to give a finite set of rules that will assure your safety in pyrotechnics. Described below you will find just some of the most important and common ('everyday') things that should always be kept in mind when handling pyrotechnic compositions and chemicals. They apply to a wide variety of compositions. But every composition is different. Some must be rammed or pressed to work properly. Other will explode when rammed. Some must be wet with water; others may spontaneously ignite when wet. Some mixtures are relatively safe to use by themselves but are extremely sensitive when used together. (A number of well known 'incompatible' mixtures and chemicals are also listed below). The point is: remember and think about the rules below, they are important, but realize any such list is inevitably incomplete. Accidents happen even in places where every conceivable safety precaution is taken. I don't guarantee your safety if you follow the rules below, but merely say it is wise to do so. It'll increase your safety.

General Safety Precautions

With that said, a list of some generally useful safety precautions in no particular order:

1. Never smoke when handling chemicals or compositions.
2. Be sure you are familiar with all the properties of the compositions you work with. Thoroughly test new compositions for sensitivity, stability, compatibility with other mixtures etc, until you are absolutely sure that the mixture is ok to use in your application and method of construction. Find out as much as you can about other peoples experiences with a particular mixture.
3. Use only non-sparking tools. Make your tools from either: wood, paper, aluminum, lead or brass. Other metals and materials may spark (especially steel will).
4. Paper bags or wooden containers are good to use for storing mixed compositions. Store compositions dry and cool. Avoid plastics, glass and metal. Avoid storing compositions in general. Make as much as you will need in the near future and keep no more in stock than necessary.
5. Never have large amounts of composition near you. If you must use larger amounts of composition in multiple items, store the bulk of composition in a safe place and bring only small amounts to your working place. Finished items should also be brought to a safe place immediately.
6. Prevent contamination of chemicals and mixtures. Have separate tools for every type of mixture (i.e. blackpowder-like mixtures, chlorates, perchlorates, etc) and clean them well with hot water and/or alcohol after use. It is no luxury either to have different sets of clothing for working with different mixtures. Wash them every time after use (dust collects in the clothing). If you have the possibility, have separate rooms or better yet: separate buildings for working with different types of mixtures/chemicals.
7. Related to 6: Keep a clean working place. Fine dust easily spreads all over your working place. Keep chemicals in closed cabinets or in a separate building. Mixtures should not be kept in the working place anyway (see rules 4 and 5).
8. Provide adequate ventilation. This is especially important when working with volatile solvents or (poisonous, flammable) powdered chemicals. Not only can you get yourself poisoned, vapour or dust may also ignite.
9. Be aware of static electricity buildup. Ground your working table. Monitor humidity and keep it above 60% as a rule of thumb. This can be especially important in winter when preparing for New Years Eve (on the Northern Hemisphere at least). Touch a grounded surface before you place things on it. Touch other people before handing over compositions or finished items. Wear cotton clothing, avoid synthetics (do not be tempted to wear fleece clothing if your working place is cold in winter). Simple things such as unscrewing a (plastic) bottle, unwinding some tape or even moving your arm may accumulate enough charge on your body to ignite a sensitive composition. The risk of static electricity is often underestimated or even completely ignored by beginning amateurs in pyre, while it is actually one of the major causes of accidents in both commercial/industrial and amateur pyre setups.
10. Wear proper protective clothing. A face shield, dust mask, heavy gloves and a leather apron are minimal. Wear cotton clothing. Hearing protection can be good but it also makes it harder to hear other people's warnings.
11. Provide safety screens between you and compositions, especially when pressing, ramming, and sieving or in other ways causing frictions/shocks/pressure etc.
12. Be prepared for the worst. Have a plan for when something should go wrong. Have a fire extinguisher and plenty of water ready. Think beforehand of what might happen and how you could minimize the damage. Know how to treat burns. Inform someone else so he/she can help in case of an accident. Have a fast escape route from your working place.

Test a device well before showing it to an audience. Inform any audience well of what can happen.