First, consider using a harness and leash rather than a collar. A cat is very flexible and they tend to be able to get out of a traditional collar. Further, in order to walk a cat (unlike Rosie) that isn’t used to a leash, may take more control. A cat harness fastens above the cats shoulders instead of around her neck. You have more control and that control is not uncomfortable to the cat.
Before you begin walking the cat, keep her harness and leash close to her feeding dish or favorite resting place. She will get used to seeing the leash and associating it with comfort and calmness. After a few days, pet your cat and speak softly to her while placing the leash and harness against her. Give her treats and sooth her. Do this a few days. Once you can touch the leash to her and not get a reaction, try slipping the harness only on her. Again sooth her with calm tones and treats if needed. Do not attach the leash to the harness yet. Allow her to wear the harness around the house for a few minutes at a time.
When you feel your cat is conditioned to the harness, attach the leash and talking calmly, guide her around the inside of the house. Let her get used to the feel of being lead. This entire process may take a few days, but when you are ready to venture outside you will see the results are worth the time and effort.
If you have a dog, take your dog and cat out together if they get along. However, never take your cat out if she is insisting on going out. Make her wait and take her when she is calm. This is showing her you are in control. Harness the cat and dog if you choose, inside the house and lead them out the door. Do not try to take her outside and then harness her. She will not yet understand the walking outside thing and she may bolt away from you.