Cynthia, by sandwiching your wood between two scraps, you are on the right path. If you are using a Forstner bit (flat bottomed bit) there is no need for a piece of wood on the top since it cuts a pilot hole and the edges of the hole first. This eliminates tear-out on the top side. This way you can make your registration marks on the workpiece and get clean holes EVERY time. If you are are using a standard, run of the mill, bit you can make a template out of cheap wood. Just make sure when you make the template, you use a backer board so you get a clean exit hole on the template to support the entry hole on the "good" wood entry hole. This method will eliminate tear-out 100% of the time.
Duct tape will work sometimes, as will simple masking tape. However, it's manure on soft wood such as pine. furthermore, it can, as duct tape often does, leave an adhesive residue in the grain of the wood which will screw up any type of finish you choose to apply unless you hand scrape the area really well. Who needs an additional step. And no, sanding does not remove all the adhesive. It will just heat it up, make it gummy, and spread it around. I might be new to ML, but I've been a woodworker since about age 10. The finished product will only turn out as good as the effort you put into it. Please don't ever use a spade or paddle bit for any type of decent wood working. They are made to rip through wood for rough holes and will never give you a smooth hole.