Watch the Locrian Application online guitar lesson by Bruce Arnold from Total Modal

The next two modes are difficult modes to work with when you are first working with them. Locrian is hard to memorize because it has so many alterations. I sometimes think of a Locrian mode as a mode where everything is altered except the root and the 4th degree. (C, Db, Eb, F, Gb, Ab, Bb) Notice all the notes are flatted except for the root (C ) and the 4th (F). Locrian is commonly used in a progression where there is a II V I cadence in a minor key, as I mention in the videos. This progression is commonly found in jazz based tunes. Just improvising with the -7b5 jam tracks might be a better practice idea to start with if you haven't worked much with the Locrian mode.
The Locrian mode has one avoid note and it is the b2 so be aware that this note will want to resolve. With the Jazz Minor mode there are no avoid notes