How do you make good decoration in a level that fits your vision?

I'm making a level right now, and I'm just tweaking tiny bits of the layout, so decoration is coming up next. What's the best way to approach decoration? I've only decorated one other time for a level I released, and it's not featured (cause it's under decorated and kinda ugly), but I want my decoration to be better this time. What process is best for this? I'm going for an industrial feel in the level. Sorry if I'm being to vague, but I'm happy to answer any questions about it. Thanks!