Personally I find it a relatively waste of effort to "promote" your hubs short-term.
Instead, I have a "companion blog" (or blogs if you cover multiple subjects) and cross reference the blog and the hubs. Stuff that's too short goes in the blog, and occasionally you can gather up the small bits, and write a hub. After a few months of steady blogging and hubbing, you'll have enough keywords to capture a steady readership, and it can only grow from there.
As hub school said, look for "long-tail" subjects. If you keep writing about same subject, you'll soon be taken more seriously as expert in the area, and if you have a brand or sorts, you can turn that to your advantage.