It’s not really that difficult. You should be able to Create a Scope of Work. If starting out I know it’s intimidating but if I was you I would at least try. There will be a lot of scope of work examples / templates on a quick search.
One easy way to do it is with a word document or google document , and just go room by room. Bedrooms are easy and simple. Write in “new ceiling fan, new paint, new flooring” for each bedroom. If doors are bad, add them. But often doors and trim can be saved so just walk them and make that judgement call.
Main living should be similar to bedrooms
kitchen, bathroom, can be a little more complex but not much, decide if you will gut them or can you glaze the shower? Can you resurface cabinets?
Mechanical systems are harder to make a judgement call on. I’d bring someone along for that if you’re really new to it.
This is a lot of upfront work but if you get the hang of it, it will go well for you. Contractors will see you as a blank check if you don’t learn to control the bids, scope of work, and make final decisions on the level of finish that you want in your property. In the long run this will be invaluable.