Impulsive habits like biting nails and lips is generally something done as a way to calm yourself down and relieve stress or boredom.
One of the things you can do to help is finding alternative ways to relieve that stress or boredom is by using fidget toys or calming hobbies hen you notice yourself biting. However, sometimes you just need something to chew on. A swim coach I know recommends chewing gum to stop biting nails or sucking on sour candy to “reset” you brain and remind yourself to stop, and I would recommend using a lot of moisturizer on your lips to stop triggering yourself to bite those as well.
It’s important to keep in mind that you need to stay diligent and constantly be reminding yourself to not bite or redirect yourself from doing so.There are also small reminders you can set for yourself like dipping fingers in lemon juice or using special nail polish to remind yourself to stop biting if it comes to that. Using lip gloss or lip balm can also act as reminders for yourself too.
Getting out of these habits can take awhile, but do your best to stay on that task and focus on yourself.