They're all good advice, but my favorites are #5 (“Don't Quit Your Day Job. Quitting a job you need to pay the bills in order to write a novel is like selling your house and putting the proceeds into a lottery ticket....”) and the last one:
“10. Keep writing. Didn't find an agent? Keep writing. Book didn't sell? Keep writing. Book sold? Keep writing. OMG an asteroid is going to crash into Earth and enshroud the planet in ten feet of ash? Keep writing. People will need something to read in the resulting permanent winter.”
Two more and he could have started a 12-step program for writers!