It is better to find a number of sites that appeal to you than listing on only one and hoping every professional in your field will use the same resource this never happens in any profession, many use more than one professional site. As in all advertising, the more a business is listed, the more it is noticed. Another bit to note is that some professional sites will create a web page for your listing. This is a great resource if you do not have a web page but would like to place more information online. Once you have it created, link to it from other listings as well.
Most professionals belong to various organizations.
Many professional organizations are online. If you find that an organization you belong to is online, check to see if they list members. Professional Community Finally, link to others in your professional community. Professionals make partnerships all the time. Place a link on your site to them and they can return the favor in kind.