1. Play the notes of a G7 chord as an arpeggio – G B D F
2. Precede each chord tone with a semitone (half step) from below – F# G, A# B, C# D, E F
3. Use any combination of the two-note groups (approach note plus chord tone) making sure, however, that you always end on a chord tone (G B D or F)
4. Be creative with your rhythms and choices of register.

how is that creative? you`re telling people exactly what notes to play.

Hello Bryan. Thanks for your thoughtful response. Because there are only 12 different sounding notes in Western music - and my suggestion uses 8 of those notes - the creativity is in how you make the combinations of ryhthm, register, note sequence, phrasing, articulation, feel, etc. Initially, you need an idea (which is what I am giving) to be able to transform that idea into something of your own.
If you have tried my suggestion, please let me know how you went with it.

I still don`t think that is creativity. Plus, you tell people to play a lot of tones that are out of the key of G dominant (or G mixolydian) and sound bad against G7 chord. Why play a major 7 over a dominant chord? I think it would be far more interesting and sound far better to use other notes in the scale of G dominant. Instead of half tones (F#, A#, ect.) why not use A naturals or E naturals. Jazz musicians have been playing off the extensions of chords (9th, 11th, 13th) since bebop. You can use these tones to add tension and color, but that`s just my opinion.

Here is lesson 2:

Repeat that same technique for all 24 major and minor keys. And you`re set. It`s actually not a bad first step being suggested here. Mastery of scales and arpeggios is the essential key to improvisation.

The trick is in the resolution. As step 3 of the exercise suggests, make sure you end each phrase on a chord tone. That way, the "dissonances" of non-scale notes are resolved, giving your improvisation a tension/release effect.