1) It's a marathon, not a sprint. And you run it alone. No matter who reads your stuff, no matter how much support you have, writing is a solitary pursuit.
2) The only variable I can control in this whole process is the quality of my own work. I can't control trends, or the economy, or the acquisitions process, or editors, or agents ... so there's no sense in worrying about it or thinking about it.
3) Number 2 is easier said than done.
4) Critique partners are essential. And I mean absolutely essential. And the choice of a crit partner is crucial, because they're like dogs and spouses. Over time, you start to resemble each other a little bit, so you better pick people whose writing you really admire. In this regard, I'm very fortunate.
5) You should always be working on your next project. Don't wait on the business for motivation or validation. And be prepared to work very, very hard.
6) You have to confront your weakness. Let's face it: we unpublished writers aren't unpublished because of our strengths. We're unpublished because of our weaknesses, so that's where we should spend our energy. If you don't know your weakness, or don't have any, see #4.
7) Money should be way, way down your list of priorities. If it's near the top, you're in it for the wrong reasons and you'll be disappointed.
8) Every writer is different, and no one's process or approach is superior to anyone else's. The ONLY thing that matters at the end of the day is words on the page. So be comfortable in your skin, be kind to yourself, find the process that works for you.
9) You will get rejected. Over and over, sometimes very painfully. To make it easier, see #5.
10) Talent is real, but it's also cheap. At some level, everyone in this business is talented, so talent alone will never be enough.
11) You can never compare yourself to other writers. It's like comparing your faith in God to someone else's faith, or comparing fingerprints. It's too personal, too impossible. No two writers will ever walk the same path, so envy and bitterness are just wasted energy that could be spent becoming a better writer. Besides, this business is hard enough without all that crap. We writers should be nice to each other.