Perhaps a better way of thinking about the task of self-perfection is to not place God at the centre of your deliberations but rather yourself. I know this seems kind of self-centred, but paradoxically it is only by focussing intensely on the inner-self that we can become entirely selfless - we must constantly introspect to detect, and work on eliminating any selfish or un-noble aspects of ourselves.
Thus this is one to way to approach the task: to imagine yourself as the most perfect, most noble, most generous, humble, selfless person you can. To imagine yourself as a being of pure love. Don't hold back anything, let yourself imagine yourself as the very best person you can possibly think of. You greatest dreams should be what you aim to be your reality. It is quite permissable to take pleasure in thinking of oneself as such, as this is not really self-love, but rather love of the divine attributes that one is making one's own, and is thus really a kind of love for God. And it is this love and appreciation for God, and His good qualities, that I predict will develop as part of this development of your own heart.
The task of perfection is the task of shaping our heart. Of shaping who we are and what we love and how we feel about ourselves. Imagining who we would like to be is really powerful. Why does this imaging work? Plato suggests that people who seek to become very good, should never act the role of an evil or bad person in a play. This is because of the power of imagination on our selves. To some degree, we become whom we pretend to be. C.S Lewis makes a similar point - we grow to fit the masks we wear. So therefore, it is of utmost importance to start wearing a noble mask, to start pretending to be who you really want to be. Do not try to please others by being what you think they would like you to be - leave that aside, consider only God as the one whom you should be seeking to please. Use His ideals of a person. Trust in His friendship alone. This is particularly important if you have low self-esteem, as that is a huge barrier to your prefection. If you dwell too much on the faults and failings of the person you are, or have been, that is another huge barrier. You must focus on who you want to be. This is how God views you, and all creation. He does not focus on the world and all its horrors - how could He see these and see an image of His own perfection? No, He focusses on what the world, and all the people in it, will become. The world and its people in their final, perfected form.
And so must we imagine things in their perfect completed form. Particularly in relation to ourselves, and then to others. I say ourselves first, as only once we can accept the absolute truth that we will be perfect, can we accept the obsolute truth that all others will be too. And then we can quite easily overlook their failings and faults, as we do our own.
Thus leave aside all your poor self-esteem, forget your sins of the past, and focus instead on preventing your sins of the future. Think of yourself in the highest possible terms, shape your heart and your love to adore the highest spiritual qualities, and imagine yourself as possessing these, and think of the blissfullness of such a being who does, as you will. Thus love God through His qualities and your possession of them. Think of the possession of them as His gift, if this helps you overcome any sense of a punishing God or one who seeks something from you (i.e obedience). God needs nothing from you, and seeks not your obedience, but only your perfection!