of sites previously created by the designer/company involved, and these should be live and online, not simply samples on their own website.
She should provide a very clear brief, outlining her own requirements, and any design ideas she might have, and ask for a firm quotation, which should cover all the work, right up to publication to the server.
She should think very carefully before agreeing to the finished site being hosted in a designer's own server space. This gives the designer total control over the site, and it could make it difficult for your sister to assume ownership in the case of any financial dispute.
She should insist on being given a CD copy of the site as it exists at the point of publication, and any usernames-passwords required to access the site on the server.
She should not make the final payment until the site is published, is working properly, and until she has the CD and access details mentioned above.
She should make sure that she provides text and any images to the designer as and when they are required, and she should check text very carefully before passing it on.
She should ensure that any contact forms return their results to an email address specified by her.
If the site is selling goods and/or services she should ensure that there is a clear indication of a postal address at which she - or an appropriate person - can be contacted by mail, and a telephone contact number.
She should ensure that there is a copyright claim at the bottom of each site page. It should say: "All text and images©(insert name of your sister's group)2008
She should ensure that any domain name acquired on her behalf by a designer is registered to her, and not to the designer, and that she is shown as the administrative contact, so that renewal notifications come directly to her.