New to SEO and need some help and advice

Hi everyone,

I'm new to this whole SEO thing and the things that I've done to optimize my site has been more or less what I've read in forums. But I'm still not sure if I'm doing it right. I was wondering if you guys can take a look at my site and tell me what I'm doing right and what I'm doing wrong. I also mentioned in a post somewhere else that my site has been getting a URL only listing. The site is not new... I think it's at least 2 years old. It was listed as the top 10 when I checked with most of my keywords about 2 weeks ago in Google Singapore (http://www.google.com.sg) and now it's gone *poof*. I optimized it as best as I could and resubmitted it. I'm also about to start on a link building campaign as soon as I get your feedback on my optimization techniques coz I wanna start clean and make sure I'm not doing anything google hates. Hope you guys can help me. Thanks a lot for any help rendered.

The site address is http://www.ntrust.com.sg. It has about 15 pages with a similar layout, and uniform ALT tags, META tags and minor modifications to TITLE tags.