Search engine spiders can only spider through text. They will use the content on your site to determine what your site is about, which in turn will help to decide how highly your site will be ranked for specific keyword phrases when visitors type them into the search engines. For this reason, keyword research is critical to obtaining natural search engine placement and should be at the top of your list when mapping out your SEO strategy.
If you're looking to upload an image to a blog post, for example, examine the file for its file size first. If it's anywhere in megabyte (MB) territory, even just 1 MB, it's a good idea to use an image compression tool to reduce the file size before uploading it to your blog. Sites like TinyPNG make it easy to compress images in bulk, while Google's very own Squoosh has been known to shrink image file sizes to microscopic levels.
Nice work Laura! This is going to be a great series. I'm working my way through SEOmoz's Advanced SEO Training Series (videos) Vol. 1 & 2 to build upon the advice and guidance that you and your team provided to me during my time at Yahoo!. Now many others will benefit from your knowledge, experience and passion for SEO strategy and tactics. Best wishes for great success in your new role.