After all the hard works when you get your site on first page, it comes the work of maintaining it there. What you do for that?
Well if you have reached the frontpage through unique content and natural traffic then don't worry you won't lose your rank at all but if another site comes out of no where and provides even better content for that keyword it will take over your spot for sure. So stay up to date with your niche and look out for competitors and match with whatever they have to dish out.
To maintain the Ranking on serp, content of the website should be unique. as well you have to promote your site for right keyword.
well, as a long time SEOzer I would suggest you to keep your site updated as quick as its possible. also add RSS feeds. Make site pages SEO friendly(static style pages.)
Since my website is classified ad site, content is generated automatically. Currently about hundred pages(increasing by the rate of 35% every month) adds up every day. Which I don't have much control of. Few things I did is changed the title, meta description, meta keywords. And did article submission, social networking. Hopefully that will help me keep it up there.
Just continue building backlinks. When I got one of my sites at the fifth position I target first position.When I got first position I target another keywords and go on!
Regular updating of the site wrt CONTENT and link building are the only two measures to be considered.
Well, you just have to work hard all the time. Getting a good position and maintaining it is really a difficult task. Original content + quality backlinks and SEO is the way.
"Local Classified Ads" I got on third position with that keyword. Now it dropped to 6. I am not sure why. I was doing what I was doing before.