The best way to practice your skills is when you are confronted with a problem and need to solve it, such as those encountered while working. It's true, to get a job, you need skills, but what most recruiters look for is: if you don't have the skills, are you able to use resources that would allow you to complete the task?
In an interview for a game developer position, I was asked how I would calculate the height of the Empire State building. For every answer I gave, they told me "You can't use that, use something else." I listed nearly everything, from Google to reading blueprints to using trigonometry with laser ranging or even using a barometer (see the barometer question). What I answered did not matter, it was how many ways I could come up with to solve the same problem.
The last job I got, I didn't even get the chance to say anything in my interview. It was the big boss talking about the company and how things work there, etc. I wrote in my CV "self-taught" and it's all they needed to know. Sure, you can describe all your knowledge on paper, but can you apply it to real life situations? Most real life situations will require you to improvise a solution (AKA a hack). If you are unable to crush the wall, are you able to go around it?
What matters the most is that you rest well before your interview, get a lot of sleep, eat well, drink a lot of water (not beer), and most importantly, be yourself. It's not that great to hire an impostor, and even worse to feel you're somewhere you shouldn't be and fearing to get caught. If they hire you and you're really unable to do the job, keep trying, ask for help from your co-workers, and if it still doesn't work, you can either quit or wait to be fired, but if you wait to be fired, it might not look good to other places you'll want to work at, while quitting could be for many reasons.