I am in the process of developing such a system for myself, but I think my situation is different than yours, and yours is different from anyone else....so Im not sure that there is a one size fits all situation
Heres what Im doing: I have 13 timeshares, 3 Wyndham weeks converted to points at one resort and 1 fixed week converted to points at another Wyndham resort, 2 floating weeks at another Wyndham resort, 2 floating weeks at a BlueGreen resort, 2 fixed weeks at that same BlueGreen resort, 1 fixed week at a small independent resort (they have a very good internal trading program) and 1 fixed week at another small independent, and lastly (for now) an every three year lockoff at a Daily Management resort that has been converted to RCI points (1/3 of the points come to my account every year)
My goal with what I bought is to use a percentage of this stuff myself but to rent some of it out to cover some of the maintenance fees...Not really a business but I have to be alert to rental opportunities and I have to advertise
The tracking system Im working on has to take care of maintenance fees, rental income and expenses. and reservations made I also keep track of holiday dates and 10 months before that, so I dont miss reserving week during good rental periods (ie spring break, easter)
First of all I have a paper file for each unit, (purchase agreement deed, correspondence, notes, rental agreements etc.
I have created several very simple spreadsheets for each function I want to track...
1) cashflow from the initial purchase , maintenance fees, date due date paid On the same spread sheet I also enter rent collected
2) I have a spreadsheet for holidays and festivals and events in the communities where my timeshares are located with the event date and the date 10 months (for the Wyndham properties) ahead of it, That, so I can reserve "special" high rental value weeks as soon as they become available.
3) When I make a reservation that I intend to rent, I have another sheet where I enter them and an advertising schedule. I color code this so its clear what has been rented and what hasn't
My real management or control is the paper file. and a calendar...Every 1st of the month I review each file and determine what needs to be done with it. (make a reservation to rent or to use myself, advertise something for rent, cancel a reservation, pack for a trip, pay a fee, etc etc) I schedule these tasks and And then when I complete a task I enter it on the appropriate spreadsheet