Twitter is easier to set up than Facebook because you can create an account in the name of the business. Go to Twitter.com and click the sign up button. It is a good idea to use a generic company email for the account so that the account is not tied to any one person.
After creating an account you can add information to your profile like your website address and a description of up to 160 characters. Be sure to upload your logo as your twitter picture. It is also a good idea to look at the design tab and choose a design that is similar to your company colors.
Twitter will scan your email for contacts who are also on Twitter. If you used a company email this may not help much. Email friends, family and coworkers the link to your twitter account, and they may follow you. If you seek them out and follow them on Twitter they will be more inclined to return the favor. Adding links to your twitter page on your website will let your customers know you are on twitter. You can also advertise on your Facebook page or your blog.
Like the Facebook page you will want to immediately fill your profile with posts and links to news, events, specials etc. Also you should seek out some informational leaders in your industry and follow them. For example if you are a HVAC company you would want to follow the EPA on Twitter. This help fill up your page as well.