The support page on the Second Life website is the best place to start. You'll find detailed information on all support options, including a direct link to the Second Life Knowledge Base and Solution Finder.
Visit the Public Help Island in Second Life and grab some notecards or talk to one of the helpful Residents that like to hang out there. The helpers will not have access to your specific account information, but they can point you in the right direction for most inworld support questions, answer many common questions about Second Life, and address questions about issues you may be having inworld.
Abuse Reporting:
You can report abuse inworld under the Help menu > Report Abuse. The abuse system should be used for reports of other Residents not abiding by the Community Standards. To find out more about submitting good abuse reports, please visit our Knowledge Base.
Bug Reporting:
You can report bugs under the Tools menu > Report Bug. Bug Reports should be filed when you encounter a problem that seems to affect more than one account on more than one computer. There are also bugs that affect single accounts and/or computers (inventory issues, software crashes), but we suggest starting with a look at the information in the Knowledge Base. We also have a Known Issues page, and a Public Bug Tracker which allow you to see what issues have been reported and are currently being worked on.