Often the first thing that writers struggle with is the first thing that's necessary TO write: having courage. The stereotypical image of a writer sitting isolated in a room for days at a time didn't just materialize out of nowhere. Writers do tend to be a little more introspective and timid when it comes to one-on-one contact. They want to release their feelings and inhibitions on the page, instead of in public. But a writer can't grow if he's isolated and his craft won't benefit from self-imposed solitary confinement. The world is your canvas and to create vibrant characters and rich settings, you'll have to get out there! Here's a few other ideas to mull around if this is your nemesis:
*The more you write and find acceptance, the easier it will be to accept criticism when it does come and stand up against it when it's unfair.
* Giving in to your fears will only make it more difficult to write and so you have to learn to cope with them, whether it's speaking in public or sending out that first manuscript.
* Don't leap aimlessly and without a plan or you may just live out your worst fear and fail. Have goals and work towards them, letting failure merely be speedbumps on your road to success.
* In the end, believe in your writing enough that nothing can defeat it.