Guardianship. Any guardians in here with advice for a newly appointed one?

You’ve been given great experienced advice. Couple of things I’d add:
Assuming your are going to DIY this (no attorney now that your past hearing stage), ask the staff in probate office for templates & samples of whatever reporting you will have to submit under the guardianship.
Also ask if there is an on-line portal to file documents with the court, if at all possible. Probate has tended to be a get yourself physically down to the courthouse to file. ((Unless you’re an atty as they get online access via their bar card registration)). But due to Covid, some courts allow you to file items as an attachment to an email; ask it will make life easier.
Make yourself a calendar with reminders of when these need to be submitted.
If documents need to be notarized, see if your bank will do them for free & if not find a nearby UPS store that does them (as they are reasonable in cost). & find a mobile notary…. you may never need one but due to Covid you might. Trying to find one under deadline is super stressy.
Try to keep a sense of humor going
& stay organized

What specific question do you have to start with. If you are dealing with someone uncooperative with all of this my opinion as someone who did POA and Trustee of trust for my brother when he was first diagnosed with probable early Lewy's Dementia AT HIS REQUEST (he being very with it and organized at the time) I found this a true learning experience I never hoped to have.
Try to take this one step at a time. First thing is get a wine box or file box and start your files of legal proceedings, assets, documents. You are going to have a LOT of files.
Secondly I would consult an elder law attorney. Your dad's estate pays for this guardianship work and you need a few hours of time to have your duties explained and to have your questions answered.
I sure wish you luck; I sure sympathize.

Always act on Dad's behalf, according to his wishes were he not unable to make wise decisions.

Still consider his requests. Share a bit, reassure him as he is able to understand during the times he will be more lucid.

Don't ever try to 'punish' or 'control' him to get your way.

Hoping to see Dad less concerned as he trusts you more, understands you are on his side, and can smile again-having less administrative concerns.

This is a huge responsibility for you. Feel free to come here for detailed advice.

Congratulations to Dad for having such a good person assigned to be responsible for his care. And to you too! 🎈🎈🎈 You've got his back!