I agree with the advice above. Use treats and praise, be patient, and work with her. Be confident at the same time -- dogs are very sensitive to their humans' nervousness and will reflect it.
Touch her body all over every day. Use a little massage while you groom her.
Bring out the clippers more than once a week, even if you just "pretend" to trim. The more often a dog is exposed to something, the easier the routine becomes.
It gets easier with age.
