Assuming you are referring to upkeep of lot, it is fairly basic:
Home sites must be kept free of all items that are not aesthetically pleasing. Building material, equipment, toys, tools, etc. must be stored in an approved shed or container. No items are to remain out side over night. Garbage pails are not permitted to be visible from the road other than on collection day. Lawn ornaments are subject to MGMT approval. Car ports and porches are not permitted to be used for open storage of items. Home owners not properly maintaining their lots shall receive notice of compliance.
(we have additional clauses for specific items, such as lawn furniture, and a clear statement that community standards are strictly enforced and non compliance may lead to eviction.)
What landlords must keep in mind is that having rules means enforcing rules. It requires that someone stay on top of the community at all times and issue notices promptly to any resident in violation. Community owners must also be cognisant of the class of their community. The lower the class of the residents the lower the expectations of the owner. The greatest offenders of community rules will be new residents. When screening you must read through the entire lease/community rules with applicants and emphasise that all rules are strictly enforced. As a example I sent a eviction notice to a new tenant that has a bird feeder in their front lawn with a metal garbage pail to store seeds beside it. I told them to remove the garbage pail and they have not complied, I issued a eviction notice with a 7 days to comply or we begin the eviction process. Do not make any rule that residents can not easily comply with or that you are not prepared to inforce.