Try, if possible, to finish in the concrete, with an action, a movement, to carry the reader forward. Never forget that a story begins long before you start it and ends long after you end it. Allow your reader to walk out from your last line and into her own imagination. Find some last-line grace. This is the true gift of writing. It is not yours any more. It belongs in the elsewhere. It is the place you have created. Your last line is the first line for everybody else.