Others have given advice on your portfolio, I’ll just add to the discussion of perseverance.
I always like to use one of my favorite jokes. (I’ll use the clean version.):
Two guys are walking down the road. A beautiful walks past in the opposite direction. The first guy asks her, “Hey, wanna go back to my place and have sex?” The girl slaps him across the face. The two guys continue down the road. After a minute the second guy asks, “Man, do you say that to all the girls you meet? Man, you must get slapped a lot.” The first guy replies with a smile, “Yeah, I get slapped a lot, but every now and then …”
It’s a numbers game. Look at it this way. Even if all the applicants are equally matched, if there were 40 other applicants, that still leaves you with only a 2.5% chance of getting that job. Learn to deal with rejection. It’s part of the game. Remember that every time you get rejected is getting you one step closer to that final success. Wear it as a badge of honor. The only people who don’t get rejected are the people that aren’t taking any chances. Go out and get rejected, do it time and time again.
You could also consider asking for feedback. After you’re rejected, you could send a note, “Hey, I respect your decision and wish you and whomever you picked the best of luck. However I am still new to this process and would love any constructive feedback you can offer.”
They may not want to, for either time or legal reasons (the reason for form letter rejections), but I’ve gotten a few tidbits of great feedback by doing this.