It already has a style, so you are just a maintenance man. You bought it so you most likely have an affinity for its present style. That's a good starting position for a beginner! You probably already know that keeping it alive is the first order of business, and that's it's easier said than done. If it is actively growing then you need to clip & grow to keep it within some imaginary profile pretty close to what is....
Clip & grow so you have layers of foliage extending sideways and up from a major branch. No foliage is allowed to grow downwards, or up so high that it interferes with the layer above. Any twig that is going to extend beyond your imaginary cloud (layer) is clipped off. You maintain space between branches for the birdies to fly through by clipping anything that grows into that space.