Name your business however you want. Make it short, easy to remember and easy to spell. It's best if you can get your chosen company name as a website domain, as well, because instead of searching many people will automatically start by typing in YourCompanyName
.com when looking for you online.
If you want to include "advertising and marketing" in your business name, or if you want to also include "promotion" or "promotions," or if you want to leave them all out entirely, that's up to you. There's no right or wrong about it.
A more specific name may help new prospects understand more quickly what it is you do. It can be helpful for prospects to be able to quickly categorize your company, especially if what you offer is cutting-edge or otherwise a little out of the ordinary.
On the other hand, a more general/generic name gives you more freedom to change your company focus and direction later on if the market changes, without having to change your company name. Examples would include companies like Radian9 and Razorfish. They offer marketing and advertising consulting, but neither one includes the words "marketing," "advertising," or "promotion" in their company name.
Bottom line, name your company however you want.