Re-optimizing onsite SEO, can it hurt?

[dmac]

We finished the re-design of our website a few months ago.  We have hired a few freelance SEO guys that were horrible. We then decided to pull the SEO work in-house.

I got nominated to do the SEO work. I started with what I thought was pretty good on-site SEO. At that time, with no experience, I was pretty proud of myself. I managed to get a bunch of our pages at top SERPs for long-tail keywords. Good enough for then. Now when I go look at the pages, I'm embarrassed to admit that it's my work. Please be kind. 

Since then I have been trying to learn as much as possible about SEO. I'm certainly far ahead of where I was a few months ago.

For the past few weeks I've been trying to focus my efforts on creating original keyword rich original content. Our competitors all have tried this, but their content is hardly readable by humans. Anyhow, we finished our fist article, it got indexed by G almost immediately and started to push our keyword SERPs up within just a few days.

Now for my question.  I have a much better understanding of on-page SEO and realize that I could make many improvements to ALL of our other pages. However, these pages are already doing fairly well with the SERPS and are moving up a few ranks a week. I'm very tempted to throw caution to the wind and completely redo all of our on-page SEO for our entire site.

Is this a good strategy?
Should I expect our SERPs to drop a little, a lot, or not at all?

I look forward to your response.

DMac

[EGOL]

Rework all of them.  One at a time. Be sure that you are making major improvement.  Improve the content while you have that page open.  Toss them back up and watch what happens to a few of them before doing all of them.

[AdoptionHelp]

I was thinking of a similar tactic as EGOL, except instead of re-working one page at a time, you re-work one element at a time for all pages. In doing the work incrementally and watching the results, you'll be making changes that will hopefully improve your rankings without rocking the boat too much.

[USHoleInOne]

Agreed, do not make a big drastic change, be patient and you will be rewarded.

[dmac]

HMMM??? Good input from both of you, maybe a combination of both.

When to do site/index.php? It stands the most to gain and loose at the same time.

I'm thinking I should start with all the things that I know are blatantly "wrong" and fix all those things first. There is no way this could hurt anything. Then maybe do some experimenting with the other pages that are currently doing well and see what the results are. Then I should know what works, what doesn't.