Don't wait until a job is posted online to target a company, instead choose the companies you would love to work at regardless if they have a current opening.
Once you have identified a target company begin to search for a key contact. This usually would be a manager in the group you would like to work in. It could also be an internal recruiter or someone who works in the same department or division you wish to pursue.
From there reach out to them and schedule a 20 - Minute Networking Meeting (aka informational interview) or send them a email or letter which demonstrate your understanding of the company/industry it's challenges and how you want what it takes to solve those challenges and make an impact.