Hello there bÆko.
i think you're trying to work on too many things at once for your first vectors.
might i suggest starting off my using stock images to 'trace' the image. please do not think this is in any way cheating as it requires a lot of practice and will help you build your abilities in skin tones and shading. i would suggest finding a large sized face to start with and taking your time carefully tracing the outlines and shaded areas for each part. ie trace the general shape of the eye, then the pupil, iris, shading for each part. you could spend hours along practicing to vector one eye.
once you have shading and colouring down then you could move on to proptions, which would be backed up by your new knowledge from working on shading.
the important thing is to keep practicing and to not be scared that something is taking hours to finish.
keep up the work