Every page should have a header that echoes the name of the page. This can be achieved by using a TYPO3 text content element which automatically assigns "Heading 1 (H1)" style to the header field of the text content element.

If you want to use other headers within a content element you should use the smaller header styles H2, H3, or H4, according to their importance. This helps readers see how the information is organized and find things more easily.

Font faces, text colours and font sizes are automatically determined by the system depending on what kind of content you have added. This helps maintain an uniform and consistent look & feel across the website.

The resolution of images should be 72 dpi, which is the resolution of a monitor.  Depending on what part of the website the images are going te be located, their size would be getween a few pixels wide to 400 pixels wide.

Images would look better and would be easier to upload if they are uploaded after they have been resized using a program similar to Photoshop.

Irfanview is a free alternative that is not as powerful as Photoshop, but in many cases can do the job.

It's very important that you only use images for which you have the rights!  While it may be easy to search for images on Google or other search engines, these cannot be used in your web pages unless you have explicitly made an arrangement with the copyright holder for each and every image.  Similarily, scanning images from textbooks is also a violation of copyright; check with the publisher to obtain permission to use any images on your site.

There are many legal sources for images - sometimes the best resources are the people around you!  You or your colleagues may have quality photographs or illustrations that perfectly suit your needs.  Also, you can try collections of royalty-free images, which can be purchased on CDs or online through sites like Clipart.com.