Here's some helpful hints that I've borrowed from my co-TA, Sarah Wolbert.
remember to keep your images small (file size and width/height)
after clicking "upload file" under posting on the upper left string, you will have an option to embed the photo within the text, or to load it as a popup image.
this also allows you to start a new entry with this image straight from the "upload file" box
if you forget to resize the image before uploading, go into the html string and enter new sizes, calculated by dividing each dimension by the same number (e.g. width1536 height 1869 becomes width 512 height 623)
flikr.com and photobucket.com - allow you to create an account (for free) and store photos that you want to use.
PHOTOBUCKET.com is quite easy to upload images
to place an image in the blog, just copy the "TAG" section and paste it into your blog.
FLIKR.com - navigation to upload pictures involves html code