You never know where your next job comes from, but one absolute certainty: the jobs for which you don't apply will never be yours.
I got my first jet job, flying a corporate Sabreliner 60, from an ad in Trade a Plane. No telling where your next job will be found.
I was once hired into a Learjet when the company adamantly said they weren't hiring. I travelled several hours to the city where the company was located, and had a cover letter and resume customized for them. I called the chief pilot from a payphone not far from the airport, and asked if it would be okay to drop by. He told me that in no uncertain terms, they weren't hiring.
No problem; I'd heard so many good things, I was in the area an d would just like to stop by and shake his hand; okay, he said. Fair enough. He had a few minutes. I stopped by, we chatted for fifteen, then he asked if I had a resume. I retrieved it from the car, and walked out with the job. You never know until you apply.
My first flying job, outside of turning wrenches and pumping fuel and washing and waxing airplanes (which wasn't really flying...but it was close enough at that age and it did net the occasional pity ride from someone with a spare seat...I begged for every one) was flying ag, directly after high school. You just never know.
Flexibility is a key; especially early in the career; be prepared to seek opportunities to gain experience, rather than simply fast track. The airlines are clogged at the lower rungs with individuals who have plenty of hours, but no experience that qualifies them to go anywhere and get a job; they've never been a pilot in command. In too big a rush to jump onto a regional without getting real experience, and they're stuck. Go for the experience.
Don't overlook an opportunity to turn wrenches, either. Good experience, and a great qualification.