Just so you are aware, "enhancing audio" is the manipulation of sounds by the use of various effects, EQ and dynamics processing. What you first need to do is figure out and understand the symbiosis between the visual and the sonic; then you can worry about polishing the sounds themselves.
Sound - music included - is supposed to be a part of the storytelling process. It can be as simple as "what you see is what you hear", providing commentary, being contrapuntal or being comedic. But sounds completely contrary to what we see still need to have a meaning and connectedness to the visuals. Only you know the affect you wish to create with your pieces. But you still have to know what emotions you wish to evoke in your target audience.
The permutations are endless. Certain harmonic frequencies and combinations thereof react upon human beings at instinctive or "learned" levels . This can be low frequencies that give a sense of uneasiness or constant "white noise" sounds that denote peacefulness. The pacing of sounds can also denote energy or calm; fast = frantic, slow = pacific. And, of course, there are the endless shades of gray in between. And there are the sound/music clichés that permeate our everyday lives - and the world of film - that communicate to us in a thousand different ways.
For your piece the "what you see is what you hear" method would include friction sounds (the pin sliding around), impact sounds (pricking the finger), liquid sounds (squirting blood), friction sounds (the brush). A comedic bent could be out-of-tune (ragtime?) piano music.
And it all comes back to "what are you trying to say?" What emotions do you want your audience to feel? After that the technique and technical aspects are merely a means by which you manipulate the sounds and visuals so that you can manipulate your audience into feeling and understanding what you what them to.
