What steps could someone take in order to keep their bokeh balls as circular as possible?
I know stepping down the lens aperture will help. Are there any other suggestions?
Would using the lens hood help?
For more about how these things contribute to cat's eye bokeh, please see:
What is the cause of this non-uniform bokeh effect?
How can I take pictures with extreme bokeh with an in-focus subject nearby?
How do you achieve sharp bokeh circles?
What exactly is this light artifact/flare?
I pretty much think stopping down is your only path of recourse or simply using a slower lens. :) I never ran into catseye bokeh with an f/1.8 lens. I only ever saw it with an f/1.2 used wide open.
A lens hood sounds like it might work, depending on the angles involved. For me, the claim that catseye only happens at the edges/corners of the frame isn't necessarily 100% true...
So, it does depend on where your light sources are, and what their angle to your lens is, and whether or not the hood can shade out the ones that are hitting at more oblique angles.