Adding in legumes to your diet can help. It adds fiber, vegetable protein and does not have the fat that meats do. Also buying them dry and cooking from scratch is a very cheap way to eat healthy.
If you want to invest in a cooking pot, get a pressure cooker. Beans once soaked overnight can take as little as 7 minutes to cook.
Soups are a easy, nutritious way to eat as well. Especially with winter coming on. Lentil soups, minestrone, etc. Pack them full of beans and all the veges you can think of (besides salad vege!
) Soups are also a very forgiving food, recipe wise.
Cut whit rice or swap it for brown rice. Minimize pastas and bump up whole grains. Wheat berries are awesome as a salad or farro in a risotto.
I try and avoid any processed grains such as flour and pasta, but making the complete jump can take some time.
Sweet potatoes are much better for you than white potatoes so when you can, swap potatoes for sweet potatoes.
For a quick dinner meal with steak is a simple pan cook on it, make a quick pan sauce with the fond and then toss in a few veges in the pan (asparagus, bell pepper strips etc) for a couple of minutes a voila, a high protein meaty meal in minutes. With left over steak, the next night slice it super fine and have a massive green salad with streak on top. Yum!