Help. Slipping down the rankings...

I am hoping you guys may be able to give me some advice.

I have taken care of the SEO of my website for about 5 years now. We have traditionally done great in the SERPS, ranking around 1 or 2 for most of out keywords.

Since July this year we have been slipping, i.e. down from 2 to 4. On some of the minor keywords we have done the opposite. BUT the main keywords have slipped.

This is basically because my competitors woke up about 2 years ago and are now pumping thousands into their SEO campaigns.

At the moment this is what I do for in-bound links:

Link exchanges
Directories
Article writing
Blog comments
Social bookmarking
Squidoo
Flickr
(just tried out Xrumer from someone of the forum too)

As to my site I am confident it is fit for purpose in terms of coding and it expands every day with fresh content. So I know this is an inbound links thing.

Any ideas people??

Appreciated....

1. May need to pump out more Web 2.0 articles (linkwheel possibility) that link to your main and minor keywords. There's a list somewhere in this form of a Web 2.0 list so that should help.
2. Ezine Articles also helps with authority to your keywords.
3. Submit RSS feeds of ALL your articles on all your properties to RSS directories. I suggest getting an RSS submission tool from this forum so that should ease the process. To create RSS feeds use RSS Mix or Feedity (search in Google)

I wish I could provide more methods, but I'm saving them for a WSO in the future lol