Keep at something even when you don't feel inspired. Don't wait for inspiration! I write a lot of songs that are terrible, in the hopes that one song that has something special comes out of it. Just stay at something, and write every day if you're writing lyrics.
You want inspiration to come in a natural way and let it happen when it's going to happen. The last thing you want is this ghost looming over you saying "it has to be good" - remember that feeling of loving what you do, and don't let the business aspect murder that. It takes away the creativity for me.
If you're just starting off as an artist, steal as much inspiration from everything you like, as much as you can. Take from books, from poets, from musicians. Just steal stuff from all over the place and then mix it up to make something of your own.
