All I really use on my mill besides a vise are flycutters, endmills, drill chuck, parallels, file for deburring, and collets. And of course a dial indicator to get things aligned.
You will want some tools to inspect your work, cheap calipers and a used micrometer from eBay can serve very well.
For layout, I usually just use a small double square and a scribe. A height gauge and surface plate come in handy for layout, but a surface gauge can work just as well. Your mill table can be used as a rudimentary surface plate.