JustUnfollow is a Twitter and Instagram Mangement App. The thing that jumps up out immediately about JustUnfollow is the attractive user interface and the ease of use.
JustUnfollow makes it really easy for you to both follow and unfollow users. After filtering a group of users you can run down the line fairly quickly.
The interface provides user profiles so you see the bio, number of tweets, followers, friends, and the head shot. While some other services provide some of this information, most lack the full detail that JustUnfollow includes.
As you can see in the image below, there are a lot different ways to go here. You might want to start with inactive following group. Following users that are inactive on Twitter really serves little purpose. Cleaning out those users should be a top priority. On the follow side, try keyword follow and copy followers. With keyword follow, you search by keywords/hashtags that are relative and/or of interest to you. Following people remains the best way to get followed.
JustUnfollow is also available for iOS and Android.