OR, when you find that your account has been suspended you can simply contact support (using the link that is given to you on the page that tells you your account is suspended) and tell them about the situation of your account.
Usually all you need to say is that you have not used any form of automation or software to manage your account including, but not limited to, following, unfollowing and Tweeting.
Explain that you really do not understand why your account has been suspended because you manually manage the Twitter account. Ask for the suspension to be looked in to further and it be lifted because you have not doen anything against Twitters T&C's.
If you've been following and unfollowing very aggressively just for the sake of trying to get people to follow you back then maybe you need to look at how you're using Twitter and what the heck you expect to get out of it by having such an untargeted following.
If you want to avoid being suspended by Twitter and end up with a very targeted, responsive, Twitter following then maybe it's time you looked closer at how you use Twitter.
Shez