Another newbie here, so just sharing some of my discoveries. Veterans may have better ideas for you.
Groceries - get into the habit of going to the grocery store more often, and buying less. One thing I did wrong was to over-buy, especially vegetables, to make sure I didn’t “run out” of proper keto foods, and then end up tossing things that went bad before I could make them. Same with meats for that matter.
I’ve also learned to buy meat when it is on sale, and vacuum seal portions for daily use and put them in the freezer. For example, buy a slab of salmon, cut it into individual portions, cook one today, seal and freeze the other portions for later use.
Veggies - instead of buying those plastic boxes of salad greens for $4.00, buy an individual head of green leaf or romaine lettuce for $1.80, then cut it up yourself and put into plastic zip-lock bags. I get about 3 good sized salads from a single head of lettuce. But you need to realize you’re going to be eating that same salad for 3 days running before it wilts on you. Just mix it up with different dressings, or add-ins (crumbled bacon, hard-boiled eggs, grated cheese, other veggies).
Other fresh veggies - before you put it in your cart, think ahead - “Am I going to eat all of this before it goes bad?” Some thing only come in size “1” - i.e., one onion, one green bell pepper, 1 cucumber. So if you are only preparing food for you, and you buy a cucumber, you should expect to be eating that whole cuke over the next 3-5 days (cucumber sticks are great with a nice full-fat dip or dressing)
Electrolytes:
I like salt on foods and have never had an issue with blood pressure (mine is great, actually, always has been), so I just alternate regular salt or “lite” salt which is 50/50 sodium and potassium. I do take a daily magnesium supplement just in case, because I don’t always eat spinach or broccoli.
Back to the cost - overall I think I am saving money eating this way - I have completely quit using vending machines at work, that’s $2 or $3 per day I am saving right there = $15 per week = 2 or 3 portions of a good steak or salmon. I quit buying any kind of soda - I just drink coffee, tea, and water now, and water is free. I quit drinking alcohol, and that’s probably another $15-20 per week average saved. I haven’t been to a fast-food joint in 6 weeks.
So keep in mind when you see the big grocery bill that it may be replacing lots of smaller bills that you don’t notice but that add up over time.