Variety is key. Currently my IRNs get
DRY: Royal large hookbill plus
Royal hookbill cuisine
Fruit cocktail
Rowdy bush pellets
TOPS
FRESH
Jalapeños
Bell peppers
Spring mix salad
Corn
Butternut squash
Carrots
Papaya
Guava
Grapes
Apple
Banana
Strawberries
Blueberries
Broccoli
Snow peas
Zucchini
Whole kale leaf
Water cress
Radishes
SPROUTS
Quinoa
Lentils
Corn
Millet
Oat groats
Safflower
Sunflower
GRAINS
whole grain veggie pasta
Whole grain bread
OTHER
occasional egg or meat, not often
Cinnamon
Bee pollen
DE
Overwhelmed yet? You don't have to be. Just focus on fresh veggies and fruits with pellets to start with. Each of us learn as we go and figures out what is best for our flock. My IRNs breed, so they need an intense diet. I have also been doing this for a while. And I will let you in on a secret; due to some personal stuff, my birds aren't getting fresh food today (GASP!). Don't kill yourself over the diet. Work hard, it is important, but lay a good foundation and cut yourself a break when you don't get to everything you want to each day. Starting with pellets and greens and one fruit is a good place to start with an IRN. Switch things out often, mix it up, and add as you get the hang of it.
As for pellets, I always buy at least one or two sizes down from whatever my bird is, it slashes the waste factor by a lot! With as many birds as I have, I can't afford for them to drop half the pellet. Remember, your bird can eat millet, so as long as you aren't buying finch sized pellets, you are fine.