Intro

If you start logging what you eat now, and pay attention to your logs plus how you feel, I'm betting you'll quickly notice which foods you find filling, that contribute well to your nutrition, that are tasty/practical, and that generally are worth their calories to you personally. What works best is pretty individual.

It really doesn't need to be more technical than that. Most of us know that lean proteins, veggies, fruits, and probably whole grains are good for us (plus usually filling), but it's also fine to include a few treats just for joy.

You don't have to be perfect from day 1. Instead, you can chip away at improvement gradually, as long as you're not starting with a diagnosed deficiency or relevant health condition. (If you do have a deficiency or health condition, ask your doctor for a referral to a specialist registered dietitian for expert help.)

Even long term, you don't need to be exactly exact on nutrients every single day to be getting excellent nutrition. Pretty close on average, a little high on specific thing(s) one day, a little low on another day on the same thing(s) - that'll be fine.

Here's a more detailed approach for remodeling your eating gradually, in case that idea appeals to you:

https://community.myfitnesspal.com/en/discussion/10636388/free-customized-personal-weight-loss-eating-plan-not-spam-or-mlm/p1

That won't be perfect for everyone - IMO no one thing is - but it's one approach you can consider.

Best wishes!