Characters simply come and find me. They sit down, I offer them a coffee. They tell me their story and then they almost always leave. When a character, after drinking some coffee and briefly telling her story, wants dinner and then a place to sleep and then breakfast and so on, for me the time has come to write the novel.
I don't always understand my characters. I write to understand them better.
One writes what one lives, even if not in a literal way. Someone who has gone through an unhappy love tends to describe unhappy loves, even if they have nothing to do with their own.
Success is something you should never take into consideration: if you follow it it'll elude you. It's important to really love your work as a writer, to read loads to the point where you can recognise blindfolded, hearing them read, the writers of yesterday and today. It's important to write every day, for hours. To have faith in your imagination and let it wander.
Writing is a solitary activity, it requires isolation and silence.
Don't wait for success, but for the respect and interest of those who read you. At the start it could be a classmate, someone who shares your interests. Before sending off the manuscript for a novel to a publishing house, it would be a good idea to try writing short stories, and publishing them in a local magazine.