I agree with S_J_B about herbs and spices. I used to just have mixed herbs in my cupboard, now I have a whole shelf of various things. I buy a lot of tinned fish like mackerel in tomato sauce, and tuna in spring water, both useful for salads or to go with pasta. Fruit and veg is a must. When I started out I stocked up on cupboard staples, in addition to herbs/spices, made sure I had pasta, rice, porridge oats, baked beans, tinned spaghetti, tinned tomatoes etc.