How do i prune a shrub that has not been pruned in about 8 years, and so is kind of spindly, not bushy?

I have a shrub – i forgot what it is, if it’s a rhododendron, philodendron, whatever, but it’s about 8 years old. I got it about 8 years ago, when it was a young thing. i never pruned it. Now it’s got a few branches that extended about 5 feet up, and of course it’s not full and bushy like it should be.

I want to prune it without killing it. Should i just cut some branches to the desired height? Is there anything i can do to make it grow fuller?