If you are not 100% confident that you know what you are doing, don't offer database design. Don't take the risk of blowing your credibilty by doing stuff that you are not extremely good at. I can offer it because I'm good with Access and my husband (and partner and resident database expert) is available to assist. I've turned down work because it was not in my area of expertise. Did it kill me to turn it down? Yes! But I know what I do what I do well and offer those services and I can sleep at night.

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Julia