Use a link shortener
It will allow you to know what works best and improve, therefore, increasing your sales as the days go by. There are several but we recommend you Bitly.
Use social media to show extras: Posts or videos are a splendid option in order to explain the bundle but, social networks are the mean to show further details your product. You may share activities you have learnt or a sneak peek of the inside.
Give the option of, if they already have your course included in the Bundle, change it for another one of yours. (This is only for authors). If you are an affiliate but have your own digital product you can give it to all the people who buy through your link *.
Reward your audience once they purchase the Bundle*.
The most common reward are digital products; whether it is an ebook or a video tutorial. Needless to say, the more value this bonus has, the more likely your audience is to buy the Bundle.