Jazz is full of common, regular chord progressions so once you know 3 or 4 of them, and can apply them to different keys and recognise them there, improvising becomes a whole lot easier.
Improvising, as you know having read most of my blog entries, is not about speed and scales. You will also be aware how YouTube videos demonstrating 'jazz piano' or 'advanced jazz techniques' are a load of twaddle and infuriate me since they just show you scales and speed... scales scales scalezzzzzzzzzzzzzzzzzzzzzz. This should be taught as being 1% of jazz piano, the rest of it being internal emotions, experiences and a selected Purpose. This is how I hope to become a successful internet presence on jazz piano instruction; teaching from the inside > out, not the outside all alone.
Approaching a IIm-V7-I progresion and playing over it and then leaving it is the foundation to jazz because easily over 90% of the jazz repertoire is based on this progression to end or even begin a song; also, to change key! I strongly recommend that you go to your piano and play the IIm-V7-I chords in all keys; if you don't like the sound of that, well, you should, but if you don't, master them at least in the keys of C, F, G, Eb and Bb, but do learn them in all the keys! I beg you.
I'll demonstrate in C in the hope that you will approach other keys in the same way. To a jazz pianist, keys do not matter since all notes are numbers (as I discuss in great detail in my eBook, available from this blog for only £3.50).
First, ask yourself what your purpose is for even playing the song you are playing. Let's suppose you're playing 'At Last', a popular jazz number in the key of C. You're at the end of the first round and you will now play over the final IIm-V7-I to start the song again but this time with a little improvisation. The song's titles refers to happiness over finding that one special love but is also romantic and slow; do not over-play the blues scales but use them on occasion, and do not over-play the 9th, a longing/romantic note. I would recommend using more chord notes than extensions (9, 11, 13) or blues notes (minor 3rd/flat 5), but that doens't mean don't use them.
We have our purpose, now let's think about a call and response idea. First is Dm7, (of the IIm-V7-I). 9th is E, b5 blues is Ab; why not have a nice run down from the E to the A flat using the notes of the chord? Thus, descending: E, D, C, A, Ab then resolving that discordant Ab to the A again, and then perhaps repeating the scale so we could start this 2 octaves higher and come down over 2 or three octaves and 'fall into' the V7, which is G7.
Now in G7, a dominant 7 chord, we can use the blues scale or treat it as the 5th mode of C, giving the major scale of C; how boring! Let's perhaps run back up but this time in octaves; but what scale? Those notes we played above (E, D, C, A, Ab) in the key of D were, in terms of note values: 9th, root, dom7, 5th, b5), but in G, those same notes are: 13th (good, jazzy), 5th (standard), 11th (clashy jazz, nice), 9th (great!) and b9 (beautiful for going back to the I, C).
Wow... let's try that and see how it sounds but this time in octaves. Forget about strict timing as if there is a metronome; play how you want, when you want. Fiddle around with those 5 notes against a Dm7 and G7 chord; you will be delighted at how bluesy and sweet it sounds at the same time. Now, do the same in Eb using the IIm and V7 which are Fm7 and Bb)!
So, instead of making a 30 minute video on fancy 'licks' and all that nonsense, we have simply acknowleged note values and combined them with a Purpose in terms of sound required, then intelligently selected some nice notes to play and applied a technique to play those notes (down over 2 octaves, back up as an octave stretch (thumb/little finger).
This is where I now say to you: go and do your own! It is useless giving you a list of licks to go and copy. What is the point? When will you use them in a song? Why would you use them? Useless, useless, useless.
It would be nice to read or even hear some licks by my readers along with a little Purposeful description.