If your publication agreement does not allow you to use your work in the ways you would like, you may want to talk with your publisher about changing the terms of your agreement before you sign it. The University of Michigan Author's Addenda can help you in that negotiation process. There are two versions: one for journal articles and similar works, the other for books.
Many publishers are amenable to changes to certain aspects of publication agreements, but they also have provisions that are "deal-breakers" for them, meaning they are unable to compromise. If your publisher is unable to change the agreement in the ways you want, it is up to you to decide whether you still wish to publish with them, even if you can't keep all of the rights you want.
If you have questions about what your publishing agreement means or using the Author’s Addenda, please email the Library Copyright Office.