Is there any step to go through before I'll apply a new cumulative hotfix to my master?

It's not the first time that I'll apply a cumulative hotfix, should I clean the old hotfix operational rules and packages?

Do I need to clean the old operational rules and packages from cumulative hotfixes before I upgrade to a new major version?

It's better to clean packages and operational rules from the older cumulative hotfix first before you update to a newer cumulative hotfix (OneOff) because sometimes the import will fail or will be partial if you don't.
Normally the mechanism is supposed to manage this but it fails sometimes, especially if you've been using our product from several versions. In this case you might have packages and operational rules in various directories instead of one: "Asset Management Platform OneOff" "Footprints Asset Core OneOff" or "Client Management OneOff". It could be a mess and packages would be replicated in these folders or not.

I have seen various types of issues: some of the cumulative hotfixes packages would not be updated, steps from the newer cumulative hotfix would be added to the existing cumulative hotfix operational rules instead of replacing them and many more. 

This should not take too much time to perform and it's always a good thing to do some regular cleanup.
 

A- Deactivate the queries or unassign the (dynamic) (device) groups from the one-off operational rules:

You might have used these objects to update to the previous one off as customers often prefer to update their relays and clients themselves (instead of checking the option to have the system upgrade their relays and agents):

- a query to list the devices that were not on your actual version yet
- a query to list the devices that are already updated or installed to your actual version

These operational rules (folders) or packages should contain the keyword "OneOff" in their name.
 

B- Clean the old one off update operational rules and packages:

Whether you are upgrading to a new version or to a new one off, the existing one off operational rules and packages will not be needed anymore.

Connect to the console as a super admin or as the account "admin" (which is better as will be sure to see all objects) then perform the following steps:

B.1 Unassign devices and device groups:

First you must unassign the devices and the device groups that might still be assigned to these upgrade rules and/or packages prior to deleting these operational rules and packages to make sure to delete them properly (this is a best practice for deleting objects in general). The operational rules folders can be called:
- "Asset Management Platform OneOff"
- "Footprints Asset Core OneOff"
- "Client Management OneOff"

Then unassign every sub rules they contain:
- delete the one off operational rules
- delete the one off operational rules folders

Note:
- Do not delete the folders containing the operational rules first or it will not delete the objects they contain. If you do delete the folders first it'll move the operational rules used to contain in the console subnode "Global settings" > "Lost and Found".
This best practice also apply to query folders, scan configuration folders and even device groups and user groups containing other groups.
 

B.2 Delete the corresponding packages

If you cannot see the "Packages" node try to connect to the console using the account "admin" if you haven't yet. This way you'll be sure to see all available objects in the console.
This could also be due to the type of license you own, it might not allow you to see the node. If you are in this case you can eventually skip this phase or request a temporary license including the "Software Distribution" module from support for the time of this import.
 

B.3 Delete the package in the master's package creator:

If you cannot see the "Packages" node because of the license you own, you can eventually skip this phase as well.

 

C- Download the cumulative hotfix/OneOff:

 The KA 000122599 will teach you how to download the latest cumulative hotfix on our website.

 

D- Apply the cumulative hotfix/OneOff:

The KA 000131608 will teach you how to apply the cumulative hotfix you have just downloaded.


Note:
Your master might not be added as a package creator. If so you'll have to add it as a packager creator prior to perform this cleanup