Will SEO approach change after Google Penguin Update?
 

What steps I need to take after this Google Penguin update ?

Make sure you aren�t trading or spamming links, remove all unnatural links to your site, have variation in anchor text and get rid of any over-optimized onpage element.

What do you think that how much time one should use a keyword daily to optimize it like in a forum's signature?

I think we can use for 10-15 post per day with same keyword

Yes i think SEO approach will be change because when google decrease your website ranking. So dont affraid if you doing right thing and follow organic SEO as well as some tips are below:

1. Avoid Hidden Text or Hidden Links on your Blog
2. Use Good Keyword Density On Your Blog Posts
3. Avoid Keyword Stuffing/Cloaking/Spamming
4. Don�t send automated queries to Google
5. Avoid Duplicate Content: Multiple pages, Subdomains, or domains
6. Don�t create Pages with Malicious Behavior
7. Avoid Affiliate Marketing Until You Have Good Content
8. Avoid Black Hat Link Building Techniques
9. Avoid Buying/Using Cheap SEO Services

I think that after updating google penguin seo made best because now in this have quality work no spamming all these are beneficial for seo.

Do all the activities that come under White hat SEO

according to me use daily 10 posts per day with same keyword .

I am also waiting the answer of that question.
very nice post thanks for sharing its here