When we begin to venture further up the neck of the oud I think it is important to observe a few fundamentals in terms of left hand fingerings on
fretless instruments.
1) Never repeat consecutive fingers when traveling parallel
2) Visualize your fingerings in groups of two, three, or four (just don't play them as a group)
3)Never finish a passage with the index finger if you will be moving back down the fingerboard
Some of this is common sense but playing at high speeds in the upper registers of the oud can be incredibly frustrating and we should use any
advantage available to us.
I've written out a little pdf file with the fingers that I use for a 3 octave Cm scale. I think, even in Arabic music, scales are great for practice
because they train the ear and the hands in terms of proper intonation.
Depending on your hand size you may find another fingering works better for you but it's still important to observe the basic principles of fingering
on the oud.