Companion planting guides are numerous, and often contain conflicting information. Sometimes even downright misinformation. I wouldn't put too much effort into following those guides. There are just too many variables involved to say something as black & white as "put plant 'x' near plant 'y'" or "separate plant 'a' from plant 'b'."

I would simply improve or maintain the soil as much as possible, and make sure the plants have enough light and water. As long as you keep in mind the size of the plants at maturity, the specific placement of various plants is mostly a non-issue.