1- All other factors being equal choose the cheapest buffer.
2- At low salt concentration, buffer contributes to total salt concentration. As you change pH, salt concentration changes. The two effects are coupled. To measure only pH effects, maintain constant salt concentration with excess neutral salt.
3- Buffers can directly influence biological systems, for example by binding to enzymes. Try several buffers to see if your system is sensitive to buffer effects.
4- Tailor buffers to meet specific requirements. For example some buffers are very soluble, others inhibit bacterial growth, others have temperature independent pKs, some are chemically unreactive, some are poor electrical conductors, etc.
5- To neutralize a solution with acid or base, use a weak acid or a weak base. This minimizes local pH extremes and decreases chances of overshooting the pH.
6- For high buffering capacity, combine weak acids and weak bases of similar pKas so both buffer.
7- Check the pH of an experiment before and after to make sure buffering capacity was sufficient.
8- The conductivity meter is a useful quality control tool. Identical buffers have identical conductivities. The conductivity electrode is more robust than the pH electrode.
9- It's often more helpful to think of pH as an acid/base ratio (i.e. carboxyl/carboxylate, imidazolium/imidazole) than as hydrogen ion concentration.