I've submitted to a couple of contests in the past (RevPit, FictionFive) and done a decent amount of standard querying. Unfortunately, I've learned that I'm a neurotic, impatient person who can't do anything but sit around refreshing my email until I pass out in the middle of the day or drown myself in work.
It's not a great system, so I knew something had to change when I submitted to Pitch Wars this year. PW has the longest waiting period of any contest I've submitted to so far, and I know it's not going to be kind to me if I spend that waiting period banging on the walls of my glass case of emotion. Hence, I did the unthinkable: I actually tried to figure out what made me so impatient and how I could fix it.
Most of my issues, I realized, came from putting too much pressure on whatever manuscript I was submitting at the time. This was especially prevalent when I submitted to RevPit. I submitted the first manuscript I ever completed (though it had gone through a couple of rewrites), I didn't have another finished project at the time (just a few chapters), and most importantly, I was deathly attached to the work I was submitting because it was the only thing I had.
Even when I submitted the first five pages of my second completed manuscript to FictionFive, I put way too much pressure on it in my head. It was a fun contest, but not a make-or-break moment for my writing career! More importantly, it was a fun manuscript, but not a make-or-break piece of work. I've realized that there's something terribly unfair about putting so much pressure on any one thing even if it's a completed manuscript you're very proud of. Working on one thing at a time and getting fully immersed in the world is great, but it can't start to overshadow everything else. Have hope for your work, but don't have blind faith in it.
Recognize that you probably haven't written your best work yet. You probably haven't peaked, especially if you've only been writing seriously for a year, like me. You probably haven't peaked if you've completed one single manuscript, or even two. Plan a new book! Write that book! Get out of your own head! (I'm mostly yelling at myself here, but feel free to take it personally if it applies to you, too.)
We've all read the advice articles that say the same thing over and over again: you probably won't sell the first book you write. You probably won't get an agent with the first book you write. We've all looked at those articles and thought "Well, I'm special! That doesn't apply to me." It does. It does apply to you. It applies to me and you and probably 99% of people who get agents and go on to successfully publish their work. You are not the 1% and neither am I, because we both need to learn how to write books before we can sell books. Building a writing career isn't a race, and it will be a long, slow process before either one of us builds up our skills enough to say "This is the best thing I'll ever write" and mean it.
A contest is just a contest. A manuscript is just a manuscript. Neither one will make or break your livelihood, but they'll both help you grow as a writer.