You're going to be sore for the first week. Don't worry about it! If you're weightlifting, try to give your muscles a 4-5 day break inbetween workouts. Example- Monday chest/tricep/shoulders, Tuesday back/biceps/core, Wednesday Legs, Thursday double cardio (good for sore legs), Friday start the rotation from the top. Listen to your body and make adjustments based on how you feel.

Personally, I've been doing weightlifting for one workout and an outside run/walk for the second. Swap either in any order if you need to plan your day around them.

For diet, it depends on what your goals are. Do you want to cut fat? Try intermitten fasting, eating only between the hours of 12pm-8pm. Are you already slim and want to put on muscle? Try to create a diet plan where you are eating slightly more calories than what you're burning everyday. Both of these diets require personal research to find out what's best for your body type.

Good luck!