Need two answer for SEO

Need two answer for SEO

Structure in SEO:

1. Instead of using underscores, use keywords in files.
2. Keep the file names in lower case letters
3. If the user reaches the “404 error” page, he/she should have a way out to navigate through your site. Use a custom site template for that
4. Design all the site structures to contain a body, H1 tags, navigation links, textual content, related links, a header, and footer.

Optimizing images:

1. Use the “Save for the web” feature of Photoshop or similar image editing software. It reduces the image size and load time.
2. Alternatively, you can use “online image Optimizer from Dynamic Drive. It optimizes the png, gif and jpeg images.