Getting one’s foot in the door.
in
This idiom or expression has to do with:
Finding an opportunity.
Using or creating an opportunity.
A. Are you having any luck getting your book published? I know have it ready
B. I don’t know anyone in the business. If I could only get my foot in the door!
History:
This has to do with door to door salesmen. Getting a foot in the door to keep it open allows you to continue your sales pitch. Once the door is closed you might as well leave!!