The best tip I have is this:
If you want people to think you are a good photographer,
only show them your best photos. Simple as that.
In these days of digital camers we all take hundreds, even thousands of photos, at every oportunity. It can help you learn and increase you chances of getting that perfect shot the more you take so its no bad thing. However nobody wants to sit though huge slide shows of these images, each one slightly different from the last. Pick a few and show these, no more that one shot of any one scene and only pick your best. The same is true of you flickr account or website gallery, pro or amateur, holiday snaps or model shoot.
Your photography will be impoved if you only show people your best photos.
More detail here:
at my blog post