To me mysticism is very much about the inner processes of our individual Soul and occultism is about working with the natural forces of nature and the energies around us to create and manipulate change. I personally associate occultism with great masters such as Alistair Crowley and then to me a great Mystic would be the Dalai Lama.
So, as such, during my own lifetime I've been involved with both - occultism as in the practices of white witchcraft, and as a psychic/clairvoyant and healer working very much on the inner realms of unity with Source/God/Goddess. Mysticism to me is about travelling inwards to find the wholeness of your own Truth - bridging the perceived gap between the divine Source and our own unique radiant soul.
I believe though that to be a good and effective occultist who deals with mystery and harnessing the power of natural forces, we must totally know how to work with the inner realms of our Soul. What we do on the inside of ourselves, our inner knowing and wisdom, effects what happens on the outside of us - what we project and manifest in the outer world. So in this way, occultism and mysticism work alongside each other.
Sometimes we may be completely out of balance with what we actually need to manifest in the world. We may wish for a new lover, a new house, a great job - but we have not yet done the inner work. We need to look deeply into our Soul connect with our deep inner wisdom and knowing. What is it that stops us from getting what we want? There may be blocks in our way, old beliefs about ourselves that we may not be worthy or good enough, that we don't deserve what we wish to manifest. These need to be shifted by working mystically - connecting inwards and examining those challenges that are presenting themselves in our conditioning and to see the way forwards.
Once we can meet our challenges and see the gift in them on the inner realms of mysticism, we can then perhaps harness the occult forces of nature to manifest what we truly desire.