If I could only teach one vocational principle to young pastors-to-be, it would probably be this.
Learn how to pay the bills outside of your pastoral salary. You’ll probably need it.
Whether you want to be a church planter or pastor an existing church, it’s likely you’ll spend at least some of your pastoral ministry being bivocational.
I’d like to add, if you are thinking of serving as a minister, don’t be afraid to put it off until you have your other vocation in hand. Church work tends to eat up your time more so than other jobs.