But remember, the modes don't follow the same pattern as above.

The main thing to remember about them is if you are playing in the most common modes, you shouldn't use the 7th chord. (The explanation involves some music theory). Just substitute the standard version of the same chord (like G instead of G7)

The most common modes are

Dorian - as used in Scarborough Fair

Aeolian - also know as the 'natural' minor

If you have a tune which uses only the 'white' notes on a piano, but does NOT start or end on C, then it is almost certainly in one of the ('Greek') modes. (In fact, the Major scale is also a mode)

Dorian starts/ends on D
Aeolian starts/ends on A