Great advice. I'm still pretty new to food forestry here are some things I've learned.
Start nitrogen fixers or something to create biomass. I went from 5 pieces of comfrey I bought on Etsy to probably 100 comfrey plants in two years. Comfrey is great for creating edge and keeping your islands free of grass and weeds. I find that you can't have enough comfrey. (Some don't like comfrey so you may want to see if you like it first.) All of my fruit trees have comfrey planted close by. At first, focus your planting in a small area and use it as a springboard for learning and propagation.
Find a trio or group of plants and just start. I have black locust, raspberries, hazelnuts, sunchokes, mint and a few other perennials that I use to start new islands. I replanted fifteen volunteer seedlings this year that came up from what I have planted.
These are all pumping out so much biomass that I can easily propagate to another area without spending a dime. Mulch, in place, as much as possible. If something struggles to grow don't be afraid to chop it down and plant something in its place.
I have a couple of varieties of heirloom apples that are just too tender but I've kept them alive going on five years. A new variety of apple that is very disease resistant and hardy is overtaking these heirlooms in growth. The new variety has only been in the ground a year.
I find that small areas that are heavily planted with biodiversity do much better than sparse plantings. You are creating a mini nursery by planting heavily.
I have an Island that is probably 50ft x 50ft and it just pumps out life. In this one area I have black locust, apple, black currant, mint, calendula, willow, seaberry, alpine strawberries, nasturtium, mint, daylilies, comfrey, Radish, Alliums, you get the point. The black locust in this area put on almost 6' this year. The locusts in less biodiverse areas put on 1/2 that growth.
I see this as a way to do less work, smarter because this growth keeps the grass back and the weeds down. It's kind of like having a nursery on autopilot. Planting less dense islands with less biodiversity has meant doing work over as grass and weeds get a foothold and the plant in place are less vigorous.