One great way of doing this is to interview for jobs that you think you're not qualified enough for. I've gone to so many interviews over the years, that after a while it doesn't matter if some company X doesn't take you. You just stop worrying. I have a couple of friends who never go to interviews, unless their skills match the job description almost perfectly. They rob themselves of chances to get more money, more…
the value of interviewing for a job i'm underqualified for, even including rejection practice and promotion potential, probably isn't worth the time and effort.
a 1% chance to earn 20k more a year and learn new skills along the way is worth more than the $200/a few hours of my life a strict cost/benefit would indicate.