do the spadework
To do the necessary preparatory work or research to successfully complete a given task or objective. Likened to working the soil with a spade when preparing to plant something. If you are looking to start your own business, you have to be sure to do the spadework first. I was up all night doing the spadework for my first case as a lawyer.
do the spadework
Make the preliminary preparations or do the preliminary research for something. For example, The department head did all the spadework for this agreement. This expression transfers the heavy spading required to prepare for planting to other kinds of preparation. [c. 1900]