• cooking instead of eating out. As others have said, having access to boiling water is a big deal. See /r/urbancarlivingcooking . If you have power (jackery?) you can [cook in a $5 thrift store crockpot](https://rvwiki.mousetrap.net/doku.php?id=food:cooking:excess_power#ac_inverter).
• paying attention to loss-leader sales and deals in store apps ($5 off $25 or whatever)
• being aware of unit pricing. For example, buy pasta at $1/lb or less or whatever your cutoff is.
• have substitutes in mind: if this thing is unusually pricey swap it for something else
• watching for “manager's specials” discounts on items about to go out of date
• clearance racks
• etc

• MIGUEL BARCLAY: one pound meals (youtube)
• Struggle Meals (youtube playlist)

Some states tax groceries; you may want to stock up before entering them:

States that tax groceries (rate if not fully taxed): Alabama, Arkansas (3%), Hawaii, Idaho, Illinois (1%), Kansas, Mississippi, Missouri (1.225%), Oklahoma, South Dakota, Tennessee (5.5%), Utah (1.75%), Virginia (1.5% + 1% local option tax), and West Virginia (5%)¹⁾