Getting your photographs noticed on Instagram is part science and part dumb luck. And while the dumb luck part is down to you, you can maximise your chances of your photos being seen by using sensible and carefully chosen tags. If you struggle with finding good tags, then this particular site should prove useful. Simply enter a broad subject title (travel, beach etc..) and the site will suggest tags to use, filtering out banned or spammy tags automatically.
You can find it here.