Sounds like to me you are jumping into the ocean without dive gear..
make your monthly estimate/quote, break it down into individual services with prices for each.
If theres that much work..
If not just give them a monthly price for all the stores..
4 stores, how much grass? How much Edging/weedeating?
How much Blowing? How often does the lot need blowed? (If needs it more than mowing..)
Those are things to consider!
Maybe if you are trying to get an idea for a price, if you include pictures of all properties with area coverage in sq feet, we can help you
What type of equipment do you have?