Get/havea/your foot in the door
Definition 1 of 1
Pro Tip 1/3Initial Opportunity
The phrase implies gaining a small yet important chance to prove oneself in a new situation. 
An internship can help you get your foot in the door of the finance industry.
Pro Tip 2/3Metaphoric Meaning
Understand the phrase metaphorically, not literally; it's about opportunities, not placing a foot anywhere. 
Volunteering at events is a great way to get your foot in the door with event planning.
Pro Tip 3/3Job Starting Point
Often used when someone is starting at the bottom of a career path, looking to grow. 
She took the entry-level job to get her foot in the door of the legal field.