Baby steps is right. You can't change all at once. It takes time. So pick 1 or 2 things and concentrate on those till you've integrated them into your daily routine. Then pick another, then another. In a year you'll be eating far better, and a year after that even better!
Butter is far healthier than margarine. The more natural, the better. I actually make my own butter from raw milk, but most people aren't willing to go to those lengths
The bread - home made sourdough bread is far healthier than ANYthing bought in the store, and fun to make! Although I try to stay away from bread for the most part myself. Carbs do not agree with me much. I keep it in the freezer so it isn't readily available.
Pasta is (no surprise!) healthier if you make your own too. I've never done this because of the carb thing, but a pasta maker is on my list of must-haves very soon because my husband eats a lot of it. If I have a craving for a pasta dish, I cook up a spaghetti squash and put pasta sauce on that. Once every 4 or 5 months I make home made Alfredo sauce and indulge myself with some fettuccine. Any more often and I'd weigh far more than I do now!
Dark chocolate in reasonable amounts is actually good for you. Again, you can buy raw cacao beans and grind them to make your own, but it isn't as good even though it's far healthier. Chocolate is one of my weaknesses - I can't seem to stop at just a piece or two. So I rarely buy any, and I never buy chocolate chips or sauce or anything. If I do I eat it all.
Have you ever made home made ice cream? What a treat. And healthy too if you use farm eggs and cream.
When you DO feel like cooking, pick 2 or 3 from-scratch meals and make big batches, then freeze them in serving sized portions for when you DON'T feel like cooking. I do this on weekend sometimes.
Try picking a certain country and make something from their cuisine that you've never made before.
Stock up your spice cupboard. Spices are the flavour of life. And experiment! Don't just stick to the recipe. Add your own touches, double the cayenne, add some cumin, whatever.
Shop at farmers markets. Get to know your farmers.
Buy something you've never cooked before and find a recipe and eat it.