Asda Weekly Grocery Haul

I used to hate doing food shop, it would just drive me crazy running around the store just to find a damn ketchup. but now I do it online from the comfort of my own home its a lot more easy and convenient compare to the store. plus I can track my spending online as it tells you how many items you have in your basket and how much you spend so far.
how do you do your food shop? do you do it monthly or weekly ? online or instore?  do you have a set budget or spend whatever it cost ?
let me know your tips and tricks I would love to know xx