Programming – unless you are a trained website programmer, then leave this to the professionals. A site that is built incorrectly can look and perform terribly and can have a negative effect on your business and actually lose you customers. It very well having a site that looks great but if parts of it do not work how they are suppose to or pages do not load, then visitors tend to get frustrated and leave.
Once your site has been built you should test all the pages and functions on it. Even though the web company should do this anyway I always advise people to check again as human error does occur and it is better that it is picked up by you rather than a potential customer. If you the site has been built with a content management system then ensure you have been adequately trained on how to use it before you do as often errors occur or websites fail when something has been done incorrectly through the CMS system.