I'm gonna post some of the common HTML/CSS tricks I've been using on my posts, under the heading [RawJournal]. (Mmm, raw, mmmmmmm... :D)
Some of them requires Text Formatting to be None. They'll be indicated as such as applicable.
And all lessons will be hidden behind <lj-cut> tags to save eyes of those who are uninterested. :D
Note: All tricks will be as XHTML 1.1 compliant as possible. This includes avoiding cosmetic tags some of you might be already familiar with, such as <center>, and also avoiding implicit end tags. This will inevitably result in a more verbose HTML code; it's up to you to modify them and use deprecated HTML 4.01 shorthand constructs (such as implicit end tags). As of right now, LiveJournal uses XHTML 1.0 Transitional DTD, which allows for deprecated HTML 4.01 constructs, so it's allowed to do so. However, such shorthands will stop working once LiveJournal converts to XHTML 1.0 Strict DTD or XHTML 1.1, so I strongly recommend you to get used to more verbose, XHTML 1.1 compliant style from now.