If anyone recommends good-tutorials.com I personally kick you in the face..."good-tutorials.com" is both an oxymoron and an ironic name considering the site's contents. (It has a few occassional uses fro some people, but is mostly a clutter of things you shouldn't read)
One generic (but very important) tip- avoid filters. You may need to, just be careful not to create every graphic element with filters...
Do user layer styles, but avoid overusing bevels.
Logical position of elements - don't make people look for things, keep clutter to a minimum, and keep things legible (ergo, pixel fonts, no matter how cool they seem, are bad unless used very carefully, and almost never for displaying actual content)
And as with most art forms, look at examples of what you enjoy, figure out why, and try to emulate that (however, avoid actually copying a site)
Do mock-ups. However rough they may seem, they can help alot in designing. And yes, on paper, as it forces you to think about it more thoroughly and in more detail.
And finally, make sure you're designing for the correct thing (don't create a hosting template and call it your portfolio layout...I've seen this sadly enough)
I'm assuming you know HTML, if not, learn it well first.
That's a list of some things I recommend. Tutorials shouldn't be necassary unless you still need to learn how to use the tools PS makes available to you. (pen, brush, selection tools, etc.)