Read, read, read! Every writer I know is an avid reader and has been from the age of five or six. One absorbs the right way to tell a story simply by reading how other people have done so.
Market research. Decide what sort of book you want to write and then take note of who publishers what. It is useless sending a four hundred page book on the Russian Revolution to Mills and Boon, for instance, and you’d be surprised how often would-be writers send their work to the wrong publisher.
Research is important if you’re writing a story set in, say, the thirties, because there’s always someone who knows the period and will pick out any mistakes you make, but if you’re writing fantasy then the only research you need is in your own head; see Terry Pratchett!
Don’t give up! I was phenomenally lucky to have my first book published, and it is an example of writing for a particular market (and in order to earn money), because it was a historical novel about Sir Walter Raleigh and his wife Bess. At that time television was showing the wives of Henry the eighth, and publishers were eager to take anything in that line. So study the market.
If you truly are a would-be writer then there will be no need for you to search for ideas. Everything that happens to you, your family and friends can end up as a storyline. Whichever way you look at it love, envy, despair and so on have been happening since the dawn of time; all you have to do is get the setting and characters right.
And do look long and hard at any criticism you receive from someone who knows what he or she is talking about. The number of times I’ve heard a writer say they will not change one word of a beloved manuscript, even after an editor has pointed out failings, are many. And it is so easy to do such changes on your PC; no rubbing out, no Tippex, no carbon copies, just delete and replace.
Don’t believe anyone who tells you you’ll never get published unless you have an agent. Of course an agent is a great advantage, but many a bestseller has been picked out of the slush pile by a sharp eyed editor.
Be sure to see that the first few pages have the reader on the edge of his seat, unable to put the book down. Most editors only have time to read a few pages before making a decision; make those pages memorable!