Just think through everything in order (the idea of making menus would be included in that). First step is going to be kashering, so figure out what you'll need to accomplish that. Depending on what you want to kasher, and what your minhagim/shitos are in this realm, that can mean getting materials to cover countertops, refrigerator shelves, cabinet shelves, etc; sink inserts; steam machine (if you hold of kashering with steam) or even m'luban (if you hold that's required), etc,; and more. Then you can move on to things you'll need to prepare food - that's obviously dependent on whether you're home for everything (sedarim, other yom tov/shabbos meals, chol hamoed, etc), minhagim and/or personal taste of what you like to eat on pesach, etc. Same goes for buying the food itself. If you're making sedarim, add on all the foods and special items you'll need for that (kosos, something for a seder plate, enough matza and wine/grape juice, hagadas, etc.).