I am often asked, where do I start. Taking dairy from my diet is overwhelming. If you can start out slow do so. If you need to cut it totally out immediately, be kind to yourself. It will take sometime to get it all figured out.
Start with the obvious and the basics. If you buy gallons of milk determine what you are using it for, and find a substitute. This is not always easy. I do not like the same dairy substitute for cereal as I do for soups, or baking. I often have multiple types of milk in my refrigerator. Non-Dairy milks often come in smaller amounts than the gallon you are use to buying. This makes it easier to use them up in the time needed.
If you go through pounds of butter, I love Earth Balance Soy Free, the one in the red container. If you can have soy the other Earth Balance varieties are highly recommended. I often use Sunflower Seed Oil instead of butter in baked goods. You could also use Canola Oil or Vegetable Oil. Just remember these oils can easily go rancid after opening. Always smell, and taste, them before using them in any recipe. Olive Oil is great on garlic bread, and can be used for sautéing vegetables. Avocado Oil is also good for sautéing instead of butter.
There are great ice cream, yogurt and other dairy products substitutes.
Once you have a handle on the dairy substitutes, tackle the rest of your grocery list. Look at the bread products you are eating and the sauces you buy. There is dairy lurking in some of the strangest places, like deli meats.
Become aware of cross-contamination. Your own at home if there are dairy products still in use in your household, and those issues caused by eating out.
If you are lost or overwhelmed, reach out. There are great online communities, and support groups. There are also people like me who have been there. I have grocery shopping services, and can come help you look through your kitchen and favorite recipes to see what you need to change.
It is doable. You can do it. SB