You bring up a huge problem. In my opinion, before we can change the problem nationally, we need to focus on the local level. Very often we have more control to exact change in our own district and keep good teachers in the field. If we can retain the teachers we have, then it is a good start.
First, teachers need to feel supported by the people around them. Building meaningful work friendships is a start. As a district staff, we can do this by pairing teachers that are new to the field with mentors that guide them in their district's policies, help with classroom management, and brainstorm innovative lessons. I've been at my current position for nine years and I still talk with my mentor teacher. She has since retired, but we developed a friendship that went beyond the classroom. I also mentored teachers and used my mentor teacher's model to help my mentees.
Parents and teachers need to work as a team to help their students become the best they can. Open lines of communication need to be developed between both parties. Many times this needs to be initiated by the teacher. In my classes, I start the year off by introducing myself to parents and letting them know we are on the same team. I go out of my way to find good things that students are doing and let parents know. That way if I have to discipline their student or if their student is having difficulty learning certain material, we already have good rapport established. With parents on my side, it eliminates a lot of stress.
The community needs to support the school by looking for ways to partner with it. Again, many times this needs to be initiated by the school. However, businesses, churches, and civic organizations are all looking for ways to support education and educators. They just need to be asked.
Teachers need to be kind to themselves. One doesn't have to have a Pinterest worthy class in order for students to learn and feel important. My classroom is stark by some standards, but my students know I care about them and I always have something for them to do everyday. I try very hard to make their learning relevant to their lives. I also ask for help. When I start feeling overwhelmed I go to my parents and community contacts and ask for their help.
Teachers need time to conquer the massive amounts of paperwork we have. Boards of Education and Adminstration can help in this need by allowing teachers work days and meaningful curriculum planning days. Teacher negotiating groups can request these when they negotiate their new contract, but boards need to be open to these needs and treat teachers like the professionals they are.
All of us, both educators and the general public, need to let our legislators know that it is important to properly fund public education. We need to elect public officials that see education as a priority. Then schools will receive more funding and they can in turn invest that money in increase wages and providing adequate supplies.
With these in place, education will be an attractive career choice. We will be able to recruit our high schoolers to choose education as a viable career. It sounds easy on paper, but it is a daunting task.