In this week's parsha (for those in chutz la'aretz), we find a discussion about waiting for the fifth year prior to eating produce outside of Eretz Yisrael. In the fourth year the produce is only able to be eaten in Yerushalayim, and in the first three it is prohibited completely. Just after this portion the Torah prohibits one to eat the flesh of an animal while it is still convulsing from being slaughtered (this translation is based on Chazal's interpretation; they also attribute to this prohibition that one may not eat prior to davening, and that one may not eat from a sacrifice prior to its blood being appropriately sprinkled on the altar). Following this prohibition are the prohibitions of acting superstitiously and divining the future through astrological means.
The juxtaposition of these mitzvos is confusing as there does not seem to be much similarity between them. Perhaps, reading these portions from the Rambam's perspective allows one a possible answer. The Rambam famously rejected astrology and superstitions as being anything more than foolishness. He writes in many places that adherence to these ideas is antithetical to Torah values since the purpose of man is to ascend from the beasts via his superior intellect and to use this intellect to serve God. By making use of these pseudosciences, one is essentially rejecting that which is demanded of him.
Thus, perhaps, the Rambam understood that these mitzvos demonstrate that one must exercise patience prior to acting. The section dealing with produce clearly shows that one must wait the necessary amount of years prior to partaking of his harvests. Not eating while an animal is still convulsing also demonstrates that one need to be patient and wait until the appropriate time arrives to eat from his recently slaughtered animal (the other examples that Chazal attribute to this mitzvah that I mentioned above demonstrate this same point). Using superstitions and astrology , according to the Rambam, demonstrate the same idea as well. Part of the reason that these practices came about was because people were quick to take anecdotal evidence and attribute the cause of many of events to these superstitions or stellar objects. Had the people thought things through a little more philosophically (or perhaps scientifically) they would not notice a true cause and effect relationship. These practices are often perpetuated due to a lack of patience to examine and understand phenomena objectively. Therefore, from this viewpoint it makes perfect sense why these mitzvos can be found grouped together. Whether or not one subscribes to the philosophy of the Rambam with regard to these matters, the lesson learned is a good one. Exercising caution and patience prior to coming to conclusions is a value we should all try to instill in ourselves and children.