1. A targeted audience
2. Solid content
Make sure that your marketing campaign on Twitter has all three components, because without them you will falter. Twitter is often not used to its full capacity by business largely because they don't completely understand it or how it can benefit their business.
For example, did you know that Twitter search is one of the most powerful marketing research tools available to help you target your audience right down to keyword or zip code. Be sure to take advantage of the advanced search. This is the right time for you to give Twitter advertising a try. It's fairly inexpensive and highly beneficial.
Twitter is approached differently by different businesses. Some will take the approach that they are providing a helpful service and therefore provide specific and helpful tips and advice. Others will take a broadcast mentality. There's no right or wrong and there are certainly tons of different strategies used. What one business finds works might not be right for another business. Keep in mind that if you are being helpful and nice people will find their way to you. It will attract them. Users tend to get rid of the broadcasters and the constant chatter that has no value.
As you grow it can be challenging to return the follow to everyone that follows you. A good rule of thumb is to return the follow to those who have authenticity in their connection with you. For example, you share a market such as tourism. Don't worry about returning the follow of those that go along and follow everyone in hopes of generating follows for themselves with little authenticity in their efforts.
Take advantage of twitter lists. You can grow your lists to huge numbers when you take the time to nurture them. You can create category lists such as friends, customers, etc and you can take the noise off your wall and organize it.
Be Twitter savvy and learn how you can get more out of your social media marketing by making sure you take advantage of all that Twitter has to offer you.