I notice that you are United Methodist. One thing that would have better helped me to prepare is getting involved in Lay Servant Ministries over the years.
Lay Servant Ministries - umcdiscipleship.org
You can often find various courses being offered through your local Conference, so look up United Methodist Conference <put your state here> and see what they have available.
Also, talk to your pastor and current staff and lay leadership about volunteer ministry opportunities in your church because you are thinking about going into some form of ministry.
You might recall that United Methodists believe that ALL people are called to ministry of some sort, not just clergy, so whether you end up called into ministry vocationally or some other way, all of the above are still very valuable.
Another good resource from the General Board of Higher Education and Ministry:
Candidacy
Also, if you are called into some form of vocational ministry and seek to become a certified ministry candidate, you will want to read The Christian as Minister (and likely will be required to read it anyway).
The Christian as Minister
This book is great at laying out all the different vocational ministry opportunities within the UMC, for both lay and clergy. Before I read this book, I thought the opportunities were limited to only Pastor and Missionary. Was I ever wrong!