Switching practice areas is very difficult, and there are many reasons. It's certainly possible to switch practice areas, but if you want to, your resume needs to give the impression that there's a reason for a law firm to take a risk on you. What about you would make a law firm want to take a risk?
The first reason a law firm would take a risk is if your qualifications are much better than the attorneys in the firm. But the idea is that what you have to do is you have to start highlighting things on your resume. Every resume must have the scent you're interested in in that practice area.
The law firm needs to be able to give themselves the idea that you will do all these things we discussed. You're going to stick to the job long-term. You have compelling reasons for wanting to do with it. Your background matches it. People must look at your resume and believe you're a better fit.
For a particular practice area, they need to read your resume and see that there looks like some reason that you would be perfect at that practice area.