It's very good thing to redirect your visitors who signup on your forms to a different page to thank them or show them a different offer or introduce them for a different product etc.
With Optingun forms, its very easy to redirect users to a different page when they signup, in the form design area, under action tab we have a toggle switch to enable URL redirection on form submission, you get field to enter your redirect URL and also there is another switch to add data to the URL, switching this ON will add user entered data on the redirect URL, that means it will pass the data that user has entered into the form to the redirect URL as GET parameters on it, with this you can access the same data on the redirected page and use that to surprise your subscribers saying a custom message like "Hey John, thanks for signing up, we have a new offer for you!"