When you get to one meal a day, just make sure the meal is a robust one, containing all the needed nutrients to fortify your body with vitamins, minerals, amino acids, those important fatty acids, trace minerals—all of it. (This can be aided with green drink powders and high-quality electrolyte supplements that will help you get your daily requirements for potassium.)
Lots of apps and website offer keto diet challenges—basically, a blueprint for the keto diet with a fixed starting and ending point (they typically last for a week to a month, though some may be longer). Speaking of apps, plenty of keto-centric ones are right at your fingertips (a.k.a., your smartphone), like the KetoDiet app, which can help you calculate your macros and track your keto diet effectively.
Think about any social situations that will be encountered, and devise ways to handle those times when temptations to eat the "old" way will be high. You don't want to be blind sided when someone at the office brings in a box of your favorite chocolates and puts them right under your nose. Likewise, a beer with your friends usually turns into a date with potato skins and nachos. Think salad and steak instead.
Note: Are you a vegetarian or vegan and want to go on a ketogenic diet? It’s still possible! Just keep in mind that the dietary restrictions can sometimes be a little bit intense. Make sure to plan ahead and prepare to aid your success. To help out, we’ve published articles (with 7 day meal plans included) for both the vegetarian ketogenic diet and the vegan ketogenic diet.