How the heck do I tend a Rubber Tree Plant?

How the heck do I tend a Rubber Tree Plant?

I don't have a very green thumb, but I've been given a few houseplants that I've been keeping at work, and they generally seem to be doing well. (They seem to really like the florescent lighting.) The Begonia is putting out new leaves like crazy and the Pothos vine is not losing any leaves, but I don't think I'm caring properly for the Rubber Tree Plant. It seems to be growing up-right well enough, but it isn't bushy and it's looking rather spindly in the middle. I pruned the top this past fall, and the new growth — also straight up — looks lovely, but the middle and base of the plant look a little patchy in comparison. My plant is quite small to begin with, only a little over a foot in total height. It has three straight vertical stems growing in a six-inch diameter pot, and each stem only has about nine leaves. Four or five of those leaves are in growing the top-quarter of the stem, following where I pruned before. I suspect that I need to prune it from the base and middle, but I'm nervous about doing that and I'd love some advice. I've done some googling on pruning and this site seem the most helpful, but it talks about starting to prune at a height of one foot above the soil line, and my plant is only a little taller total than that starting point. Can I still prune it anyway? I've only ever pruned from the end of a stem before, never from the middle or the base. I just lop off any leaf? Flush to the stem? And then nick just above the node? How far above the node? Like, a sixteenth of an inch? And how strongly do I make the nick? Until I just break into the stem, or until sap comes out? Would it be excessive to prune two leaves from each stem at this time? Sorry to load you all up with questions, and thank you very much for your help!
Can I get it to bush up?

Can I get it to bush up?

transplanted from my compost pile…

transplanted from my compost pile…

My bedroom

My bedroom

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Plant ID help!

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