Everything that I would say has already been said by these amazing, experienced ladies. I will reiterate that with my nearly 6 years of scrapping, I have been turned down more times that I have fingers and toes. It took me probably close to a year to get accepted to my first CT and after many years learned and many tears (because I cried with every rejection as well) that you really should only apply to calls for designers that you absolutely LOVE and fit your style and tastes. You can apply to so many CT's and then start getting that YES and before you know it, you have way more than you can handle. If you get a no.....take the advice of so many others and study that designer's other CT members styles, techniques, etc. And as Jacinda said, check out those tutorials. We all always have room for improvement.
I too have been on the other end as a designer and no's are SO HARD to send out. Designers really do most of the time wish they could say yes to all applicants and make their day but, there are so many reasons why they have to say no and you should not take it personal. Because you know, I have had designers tell me no that I am great friends with and they seem to love me as a person and compliment my layouts all the time. So, I know they aren't trying to hurt me or saying I am not a good scrapper.
But just don't give up sweets, if you do you will never get the yes's you are wanting. Keep your chin up doll and #1 keep scrapping and improving just because you enjoy it and are preserving your memories.
Hugs!