I quite like this set of articles from Melisa C. Michaels for beginner writers: http://www.sfwa.org/tag/melisa-michaels/
Most of it I have seen elsewhere but it is still nice collection of pointers. I quite like Michaels' Skyrider series, an enjoyable science-fiction romp which is now sadly out of print.
Nicola Morgan's helpIneedapublisher blog is a great resource for further writing advice, which often generates interesting discussions in the comments.
The Guardian published a whole set of rules from a variety of famous/successful authors, all inspired by Elmore Leonard's 10 Rules of Writing. Entertaining and relevant stuff, most of which highlight the need to be well-read and that writing-writing-writing is an absolute must.
If you are looking for direct feedback on your own writing, both Nicola Morgan and Nik Perring offer their services to this effect (here and here respectively). There are probably lots of authors doing the same but both of the above are superb, talented writers and have had good feedback about the services they provide.
Finally, it is worth going to the NaNoWriMo website, the pep talks provided there for the participants contain a wide-ranging smorgasbord of writing advice from, again, many a successful author, and they are entertaining to boot. Plus, you can join in this year's challenge, if you are feeling brave that is.
Now go and write something (and that goes for me too).