Integrating permaculture into an existing garden

I've been offered a chance of taking care of a garden that has been abandoned for a couple years. I have little hands-on experience with permaculture (or gardening in general) and I haven't been there yet, so right now my priority is to learn how to observe garden ecosystems, so that when I soon visit this place I can make any meaningful conclusions. The plot is in a rural area in central europe, next to a forest. We are in early stages of discussion with the owners so I don't know much, but there are nut and fruit trees and I can expect the entire place to be a bit overgrown.

I already started reading Gaia's Garden, but what resources would you recommend to have any idea where to start and what to look for?  

When you get to see the garden maybe posting pictures here will help folks give advice.

Start by implementing practices such as composting, mulching, and using compost tea.

You will want to work towards creating an ecosystem.

Best wishes and I am looking forward to the next step.