I believe a healthy CONSISTENT diet is key if you want to see any benefits from it. I eat pretty much the same kinds of things for lunch the last 2 years and it works great. I think breakfast is very key also.
Honestly you don’t need to be super picky and write down what you eat every day and count your calories. My coach is good friends with Alan Webb and asked him about his diet many times Alan ate the same thing for lunch every day in high school a sub along with other snacks. I either eat subway or bring my own sandwich fruits snacks, yogurt with oats to add baked lays chips (healthy version) and water or milk. I always eat similar things for breakfast oatmeal, eggs, bacon, toast, orange juice, fruits, cereal… So many healthy options hard not to eat healthy you just need to get yourself up and get it in.
And as far as supplements I believe strongly what Steve Magness preaches on his website and via twitter. He believes multivitamins are bad long term. I myself take a calcium,mag, zinc with added vitamin D once or twice a day along with fish oil. Vitamin d and calcium have strong evidence to reduce musculoskeletal injuries. And fish oil reduces inflammation and helps you recover. Salazar thinks this is an important one.
Good read here about supplements also
Just get healthy foods and learn how to read labels. Whole wheat pastas and breads, fruits, veggies, fish, chicken, lean beef, milk, beans, spinach salads. So many good options out there.