Japanese maples love a forest type environment. That would mean adding composted organic matter to the soil throughout the planting area. This can be added soon after planting just don't rototill or spade so close as to damage the root ball. These trees love a little morning sun but appreciate some late day shade although this is not absolutely essential. Keep the soil moist and wait to fertilize until new growth begins in the spring. Don't worry about the branching now. Over the next 2 or 3 years you can do some pruning here and there to shape the tree as suits your aesthetic preferences.
Hope this helps!
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