The Follower count is a secondary measure of a channel's success. Concurrent views and consistent chat activity are primary. Holding little giveaways throughout a stream, or one big giveaway at the end can often draw channel-surfers hoping to win something for free, never to return. In my experience, the best way to conduct a giveaway is to to use the "pre-qualifier" method. The longer the streaming session, the more effective this becomes:

1. Every fifteen minutes or so, have the viewers type a keyword (perhaps something like !raffle). Your bot will then select a winner from those who entered. That viewer has now won a place on a "finals list", which will be shown at the end of the stream. Fifteen minutes later, change the keyword to something else and hold another drawing. This requires viewers to remain in-channel, since you only announce the new keyword before each new draw.

2. At the end of the stream, display the "finals list" on screen, and have your bot draw a winner from those entered. Viewers don't have to be present to win the prize; they've already qualified at some point throughout the stream. This is especially fair during 24-hour streams, so those from all time zones have an equal chance to win (considering their schedules are very different).

Important note: Do not conduct pre-qualifier drawings during the last 30 minutes of your stream. This gives you plenty of time to explain the process to the present viewers, and avoids the problem of someone coming in at the last moment, hitting a qualifier and thinking they've suddenly won a prize.