I certainly haven't given up processed foods, but actually all my main meals are made from scratch. My advise would be just stock up on lots of great recipes and follow them ! I know it sounds simple but that really is because it is!
Instead of saying "what foods should I buy?" I go through recipe books, find seven meals, write down what I need for them, and buy my shopping that way. You'll quickly get to learn what things you'll be buying differently without processed food and it will become more natrual, but that way you wont be overwhelmed in the supermarket not knowing what to buy now you're changing your eating habits!
I also agree to start off simple, stir frys, pasta dishes, casseroles, curries, things like that. Don't be daunted by lists of ingrediants though, because a recipe might have loads of spices or herbs in it - but that doesn't nessersairly make it difficult (read through the instructions to see), but if you avoid recipes with lots of spices/herbs/other-flavourful-things they'll be bland and you might get disheartened! I have a favourite recipe with a list of ingrediants as long as my arm, but you litereally just chuck it all in a pot, you don't even fry the onion first! So yes, don't be daunted.
Also, it's up to you of course, but you don't have to go all-or-nothing, if you just reduce the amount of "processed"/junk food you eat that's really good, but you might find it easier to keep the occasional treat/lazy-day-meal!
I have a feeling that if I deprive myself of something (like chocolate, which I'm deffinatly not up to making myself!) I'll just want it more.
Anyway if you're more specific we may be more help, but that's just some general experience of mine