Whilst "Mugshots" are particularly useful for a "who's who" page they should be avoided in most other places - try to use photos that tell a story or say something about what you do. If you want to take portrait style photos here are some handy tips…
Take the pictures at the same time of day where possible.
Use the same location to give consistency.
Not against a busy background - a hedge is good because it gives texture without being too distracting.
Take a few photos of the same subject just in case!
Make it fun! - Find a way to make people relax and smile while you photograph them - you don't want the world to think you're a miserable bunch!
Make sure people know what you're doing with their photos and that they're happy for you to use them on your church website.