Get a pressure cooker. It is so great to be able to prepare dried beans or brown rice for dinner after work, or make a tough cut of stew meat falling-apart tender in under an hour. I almost never use my slow cooker any more because I like doing it fast in the pressure cooker instead.
Cut up veggies and large fruits for several days all at once and put them in containers in the fridge. There are also little reusable containers available that you can parcel out hummus or another condiment into, so it's easy to take for lunch.
When you make beans, rice or quinoa, make extra and freeze the extra portions, or keep what you can use in another dish within a few days in the fridge.