The best Twitter marketing software that I know of so far is LabTweets. Due to the number of the tools it has and the wide range of usage Labtweets is considered to be the SwissArmy knife in twitter marketing. Once you buy of this, you can use it forever. Not only that you can follow people in twitter, you can also follow their followers giving you acces in building a targeted network in an instant. Some of its features are even offered individually by other softwares. You can look for it online by searching it on google. It is very easy to order and install.