I would explain how to customize Blogger templates’ header section for better search engine optimization and now read the rest of this article to have better Google search results  for your blog.

Since title tags have absolute impact on your search engine ranking, you must optimize your title depending on your main target keyword. If you have a blog about “Blog Widgets” your home page title tag must include the keyword “Blog Widgets” too. Thus Google bots will understand that your main topic is “Blog Widgets” so, as you update your blog content regularly and get backlinks from other widget related blogs, your SERP will improve automatically.
Find these lines :
<title><data:blog.pageTitle/></title>
Edit:
<title>My Main Keyword – My Blog Name</title>

SEO Tip #2 : Single Post Page Titles
It is always better for SEO to have a single post title like:
My Article Title –My Blog Name
But Blogger shows the reverse version of the title type above, in order to fix this bad SEO title type :
Delete these lines :
<title><data:blog.pageTitle/></title>
And add these lines for better SEO
<b:if cond=’data:blog.pageType == &quot;item&quot;’>
<title><data:blog.pageName/> – <data:blog.title/></title>
<b:else/>
<title> <title>My Main Keyword – My Blog Name</title>
</title>
</b:if>

Meta keywords and other meta tags are not important and not cared by Google bots. So do not be busy with adding unnecessary tags since only description tag is counted by the bots. Most Blogger blogs do not have meta description tag and thus they lose traffic and rank worse. In order to recover this loss you must add a meta description tag for better Blogger SEO.
<META NAME=”Description” CONTENT=”Your blog description with a few keywords go here.”>

Older blog posts are more likely to rank higher in search engine results, in order to help them gain some inbound backlinks and boost their ranking, you should give links to them in your related articles. Be sure to choose a keyword as an anchor text.

Be sure to have a few and related “keyword” labels, for instance, if you have a blog about “real estate”, your blog categories / labels must be like “Miami Real Estate, New York Real Estate” etc.

It is recommended to have post excerpts on main page and labels / categories page in order to reduce the amount of duplicated content pages. Additionally, showing full posts may be reduce the load time and this may lower your SEO point, as you know Google cares your page load time.

It is highly advised for bloggers to add alt tags to images,since Google pretty much cares image alt tags and describes images according to the tag. Here the simple image code with alt tags.
< img src=”IMAGE-LINK” alt=”your image description goes here”>
I am going to expand my SEO tips lists as I learn and remember. For now you can apply these SEO tips to your blogs and rank better.