There are many responses to these sorts of questions - workshops to attend, lists of 10 'secrets' to attract your perfect soul mate, 12 steps to manifesting your twin flame, and so forth. It can be important to experiment, with openness and curiosity, any approach that you feel drawn to.
The suggestion I usually make, though, is not nearly as sexy or compelling, or all that fun or flashy: learn how to take care of yourself. Learn how to practice radical self-care, self-kindness, and self-compassion. For to the degree that you are able to take responsibility for your own vulnerabilities and core emotional wounding, it is to this degree that you will release your partner from this burden, which is not his or hers to carry.
So what does it mean to 'take care of yourself' in this context?
By 'taking care' of yourself, I mean becoming very curious about your emotional triggers, about the feelings you do not want to feel - about your addictions, habitual behaviors, and how much you complain about and blame others and the world for your existential flatness, dissatisfaction, rage, and profound feelings of disconnection. Be willing at times to travel underneath the narrative, the very compelling story of 'me,' and make experiential contact with those emotions and sensations that you have abandoned - and at times are seeking in your partner. Make a commitment to stop complaining about your life and instead provide a sanctuary within you for your feelings, emotions, hopes, dreams, fears, and fantasies to unfold and illuminate.
Practice being kind to your feelings and emotions and you will naturally be kind to those intimate partners that are sure to trigger them in you. As long as we are looking to our partners to fulfill those functions that were not offered to us as young children, it will be difficult to come into a fulfilling, loving relationship that is not riddled by the pain of projection. Your partner is there to help you, to support you, but not to take care of or parent you. They were not put on this planet to do your work for you, but to skillfully support you as you turn toward, meet, and metabolize what has been knocking at the door of your heart for so long.
Perhaps there is no 'secret' to co-creating a fulfilling, supportive, mutually beneficial intimate relationship, as it is always in the end, a movement of the unknown. Intimacy is not something we can come to, figure out, or 'solve' by means of conceptual and egoic process, and may never, ever be resolved into a magical formula. But by learning to take care of yourself, you are creating a foundation upon which the mystery of intimacy can unfold, dance, and come alive within you.