Today's tip is to read visa applications very carefully!
First of all, some visa applications have very different requirements in terms of the type of photos that are required. For example, some countries require slightly different dimensions in terms of photo size.
Additionally, in the Philippines, for instance, instructions on the visa application require that visa application photos be taken without glasses.
Some countries also request more than the standard two photos that are required on the majority of visa applications. This is particularly true of nations that are very careful of foreigners they permit into their country.
My suggestion is that all visa applications be read carefully, preferably with a "highlighter," to "flag" or emphasize unique requirements.