Why add a tailgate domain name to your advertising plan? Consider the domain name you use now. Is it easy to remember, spell and type into a tiny mobile device? Could your business benefit by adding a second name that tells what you do in no uncertain terms?
Yes, and you probably should. Whether it's called "pointing" or "redirecting" or "forwarding", your webmaster can easily make any domain that you control take people to any page on your website that you'd like. Maybe that's to your home page, or maybe it's the page on your site that deals with that specialty. It might even make sense to add other domains for other specialties too. Ask yourself what your future customers will type into an online search to find you - including WHERE you are, as well as what you do or sell.
You can use any combination of words that you'd like, providing it hasn't already been taken. Remember that DOT COMs are by far the best because they're easier for the public to remember. If you have a dot net for example, chances are they'll remember it as dot com, so it's best to have the dot come in the first place.
Only you can answer that, but think about people who don't already know you: If your main domain is hard to spell, or hard to remember, or if it doesn't convey what you do in a word or two, then it may be a liability rather than an asset. If this domain fits your business, it could be an important source of new customers for many years to come.