You're going to love the garden even more if you take a little time to create a plan. 
Figure out what you want in regards to color, shape, size, blooms ... figure out if you have sun or shade ... figure out if you need to block your neighbor from view ... figure out how much time you want to spend doing the work to maintain the plants ... think of what will bring you the most joy. And if you can't think of what you need to think about - have a listen, we tell you.