Where to begin with Oracle and SQL
Here is my list and everything on this list is excellent. I’m sure I missed a few good ones, but maybe people can add them in the comments.
Start with Oracle Docs, they are free and good!
Get the best books and read them
A bit old, but this is a great overview of Oracle: Practical Oracle 8i by Jonathan Lewis
After you have read the above, dive into the important details:
Oracle Wait Interface by R Shee, K Deshpande, K. Gopalakrishnan
If you know SQL but want to get great at SQL performance, read these books
Relational Database Index Design and the Optimizers by Tapio Lahdenmaki
Join Online discussions and follow blogs
Oracle-L forum: www.freelists.org/list/oracle-l
OTN forums: https://forums.oracle.com/forums
Oaktable blogs: http://www.oaktable.net/oakienews
Create your own Oracle blog aggregator, here is mine: http://oracle.collected.info/
Go to conferences. First of all your local Oracle user groups and if you have the time and resources then go to the bigger conferences: