Variable names (and ofcourse class/procedure/function names) are IMHO the most important thing to do right, because this is the only text you usually read apart from the comments. Using a load of comments to compensate for bad naming is just bad.

Some things I also find important are the more subtle aspects of a coding style. For example, I find it annoying when someone writes his code using capitals everywhere (Especially for the reserved words: IF, BEGIN, ELSE). Because capitals are very attention-hungry, I tend to use them as least as possible. I think JAVA has pretty good conventions regarding case. They use lower camel case for variable/method names and upper camel case for classnames. Finally they use capitals for constants (were compound words are separated by underscores). I find this convention very nice, especially because allmost everyone uses it. I wish there was such a clear consensus within the pascal-world (Allthough I DO love the T, P and F prefixes, there is still quite a bit of freedom in using different case )