I've never understood meal planning, because the meal is only ever going to be as tasty as its ingredients. And if the ingredients aren't in season or are super expensive, then it all goes out the window.
So, I shop first, plan second. I see what looks good, what's in season, what's on special offer (to eat now or freeze for later). I start with vegetables, then add a protein and that generally dictates which carb I make. I always have chicken and beef and ground pork in the freezer. I have a well stocked spice rack and pantry with grains, pulses, pastas and tinned tomatoes and vegetables. I have lots of condiments.
It's not that difficult, for me, but I appreciate I have the time to do this. I shop once a week, cook three-four times a week (always make extra for lunches the next day), get take out once a week, have omelettes/sandwiches/quiches for lunch at the weekends because life is hectic - and always have tonnes of fruit and a fairly decent amount of junk food (ice cream, tortilla chips, etc).