I wrote a book about solo ki exercises - but sorry, it's in Swedish. If you're fluent in that tongue, here it is:
A few tips:
Breath and ki are as inseparable as siamese twins. Work on one, and the other is stimulated, too.
Extend your breathing - that is, continue with a spirit of breathing out, even after no more air comes, and vice versa with breathing in.
In any kind of movement, if it is outward (e.g. pushing) do it as you exhale, and if it is inward (e.g. pulling) do it as you inhale.
Try looking at something far away, or pointing at it, while breathing out. Close your eyes or lower your arm, before your exhalation ends.
Try walking forward on an exhalation, stop before you inhale, and then walk at the next exhalation.
And so on.