Ditto on location. Much of bonsai is very dependant on climate and time of year so knowing where is just as important as knowing what.
There's always several different options to develop bonsai.
At this stage you probably have 2 main options:
1. Prune and trim into a small tree shape. This will slow development so you will have a small, skinny bonsai for many years but that's Ok, especially for a first tree.
2. Let it grow. Lots of growth = quicker thickening so it will develop a decent trunk much quicker then in a few years style the branching to make a much more impressive bonsai.
While you decide learn how to keep it alive.
If you go with option 1 and want suggestions on how to shape this tree we will definitely need to see the trunk and where branches are growing from in order to make informed decisions. No mean feat to take good photos of a tree with such dense foliage.
Usually, very young junipers like this can be bent and pruned into almost any style so one style is not really much better than another.