Can I share the proposals I've written for one client with potential clients?

I am a freelance proposal writer, and have been approached by potential clients asking for samples of proposals that I have written. I have some, but they were written for other organizations. Are there any ethical issues about sharing these with potential clients?

The proposal belongs to your client organization. If you would like to share a copy of the proposal as a sample, you must get permission from your client organization first. Another option is to recommend that potential clients talk with previous clients about your work.