I don't have any experience with rescues, but the same tips for training puppies may apply:
Schedule grooming time when Poppy is tired, after playing or walking, whatever her favorite activity.
Introduce grooming in short increments and gradually increase. Maybe do a little every day so that it becomes part of her routine.
Maintain a calm and confident demeanor. If you are nervous or anxious, Poppy will mirror you. Talk to her in a reassuring, soothing voice telling her what you are going to do and to praise her. Give her a massage, let her sniff the utensils but don't let her chew on them.
Poppy may be more comfortable starting in your lap on the floor or in a chair, or she may do better on a counter. You will have to gauge what works best.
Give praise and small treats to reward each small stride in accepting grooming.
Hope some of this helps. Bless you for rescuing this girl.
