Considering the infinite variety of logo possibilities, the consensus of opinion about logo design is pretty solid. For starters, the visual symbol of your business needs to be unique for legal reasons. It should be eye-catching for business and marketing reasons. If you can also manage "professional, creative, stylish, fun," many people agree that that's awesome.
Professional logo design can be seen as a luxury. Your own name or your business name may be unique in your industry. The way the name displays in your letterhead or signature may make a good logo. Many startups that invest in professional web design, web development, search engine optimization, and interactive software can economize on logo design. If the "logo" automatically generated by signing or typing your name isn't excellent enough, you can always add an updated logo later. So, when you invest in professional logo design, what can you expect?
A professional designer should do the research to make sure your logo looks different from other logos that might be associated with a similar product. As we learned recently, many people don't pay close enough attention to notice that your apple and someone else's apple face in different directions.
Some logos contain an iconic element that looks distinctive enough, even in a tiny size, to become a "favicon" that displays on a browser tab. Favicons are, technically, different from icons, which symbolize operations like "close tab" and are increasingly standardized. Favicon uniqueness is not mandatory. However, readers who frequently open pages from, e.g., Google and The Guardian on separate tabs grumble because their "g" favicons look too much alike. If you pay someone to design a favicon, it should be a nice, clear, unique one. (The Webstasy "w" doesn't look like the Wikipedia or WordPress "W.")
The best logo designs are memorable and attractive, yet also clean and simple enough to be recognized even on a small scale. People think of logos like Coca-Cola, Ford, or Windows as successful designs partly because these logos are associated with successful products...but the logos also happen to be elegantly simple, scalable, and recognizable. (Like the football-shaped C that's replaced the elaborate bear image in the Chicago Bears' logo.)
A good logo can be recognized in black-and-white even though many good logos use color. Customers may view your web site or print out your correspondence on black-and-white devices; some customers are color-blind. Your logo should look clear and unique even when it appears in black or gray.
Individuals are "professional" when they're good enough at whatever they do to earn money for doing it. That would apply to almost any business. For businesses, a "professional image" means "more like a teacher's, lawyer's, or doctor's office than like a store, a factory, or some other kind of business." You may or may not want a logo with a really professional image--dignified, elegant, conservative, and modest, probably consisting of plain black or dark blue lettering on a white or pale beige background.
If your business is more innovative and creative, like a design business, you might want a more innovative, creative, or stylish look. Colors, fonts, and simple graphics can give a logo a hint of creative flair without sacrificing elegance and accessibility.
If your target market includes children or appeals to the childish side of adults, bright colors and cartoon motifs can be described as "fun." While I like web sites to look serious enough to keep their grown-up cred, a logo for, e.g., a snack company can have a touch of kid appeal and still maintain an air of adult competence.
Many businesses have more than one logo, perhaps for different products or uses. As a web design company, we can work around your existing logo design, or help you add, update, or replace one.