I'll have my husband weigh in on the topic...
He does have any number of books and websites to recommend. As someone who isn't Keto herself but lives with someone that is, I can share a few things.
First thing, keto is a bodily process more than a diet. You train your body to burn fat instead of carbs -- if you continue to eat carbs you will fail at keto. It won't work, yes one piece of toast means you failed the entire day. It's not a temporary fix, most people don't succeed in keeping the weight off if they just go Keto for awhile, it's a lifestyle and its mostly meat. There are high fat options like nuts, olives and avocados, and extremely low carb/calorie options like pickles and the basic lettuce, celery, onions and mushrooms.
Try going low carb/high protein first... when I am eating well I'm around 60 carbs per day. Right now I'm probably over 100 but that's still within my guidelines. Any low carb/high protein diet will work, I mostly use diabetic guidelines because while I've lost 100 pounds, my goal was to reduce my blood glucose level -- which I've done very well. My guideline is "nothing white -- no wheat, no rice, no potatoes, no pasta, no baked goods..." Once you get those things out of your diet, going keto won't be such an abrupt change.
Starting about 3 years ago, my husband was basically 400 pounds and is now about 180... He lost the weight the first couple of years and has maintained for a year now. He has combined Keto with intermittent fasting, that is he has an eating window. He still weighs and records every mouthful he takes, you can use a notebook but we used
https://www.myfitnesspal.com/
My husband had a supportive doctor and went in for regular 3 month check-ups, including blood work and self-paid DEXA scans. While mostly prescribed for bone density, they also tell you a lot about the amount of fat and how it is distributed. It was much less expensive for him to buy a package of multiple scans from the private company for the same cost as one through the hospital (which insurance wouldn't cover anyway).
https://dexascan.com/