Watch the Lydian Flat Seven Scale online guitar lesson by Bruce Arnold from Total Modal

The Lydian b7 is commonly used over a dominant 7th chord. It one of the fee dominant modes that doesn't also work over a 7sus4 chord. This is because any mode with a #4 or b5 won't work because that note isn't an available tension on a 7sus4 chord. It is easier to memorize a Lydian b7 mode if you think of it as a Mixolydian mode that has a #4.
The Lydian b7 has no avoid notes.Remember that with the modes that you don't know as well, improvising will really help you eventually understand the sound.
With every practice session you need some fun otherwise you won't want to come back to it each day. If you only have one hour to practice then I would devote 50% of your time to exploring the guitar for the fun of it. This might include learning songs, improvising over songs you use in your band, or working on extended techniques such as tapping. Basically do whatever you want that gives you enjoyment.
If you have two hours to practice I would spend 25% of your time just having fun learning tunes, improvising or working on material for your band.
If you have more than two hours I would spend 25% of your remaining time doing things that you enjoy on the guitar. These could include:
1. Learning solos
2. Learning new tunes
3. Practicing extended techniques
4. Jamming with jam tracks or other progressions
Concepts that you can use in tandem with Modes
If you have more than two hours to practice you can begin to apply scales in other ways to improve.