12 Essential Tips to Using XBMC as the Perfect Media Hub
Quick Tips and Troubleshooting

MTU Settings for Windows 7 SMB Shares
Some users have reported problems with SMB Shares for XBMC after upgrading to Windows 7, such as dropped connections, no connection at all, and other quirks. If you're running into these or similar issues, you're not alone, though it may take some trial and error to resolve.
XBMC.org forum member Aikar has posted MTU settings that he claims got everything working again (see here). We didn't run into issues ourselves so there's no way for us to know if his method helps, but it's worth a shot if you're at the end of your rope. Also take note of the last post on page 1, which seems to have also worked for at least one other forum member in that thread.
CPU Usage Unusually High
If you're still chugging along on a Pentium III or AMD Barton chip, it's high time for an upgrade. But if you're running a relatively modern CPU and notice that just navigating menus results in ultra-high processor cycles, then there's a problem, albeit a seemingly common one. The verdict is still out on what does and doesn't work, and what causes the issue in the first place, but one thing that has worked for many is to disable VSync. You can do this in Windows and in XBMC, but try one at a time before disabling both.
Also check to make sure that all your drivers are up to date, including GPU and chipset, and that you're running the latest version of DirectX.
No Video - Only a Black or White Screen
There are two main culprits that could result in a black or white screen instead of video playback. The first is if you're running an older videocard that doesn't support Pixel Shader 2.0 or higher. If this is the case, then you're "out of luck," as XBMC's developers put it.
If your videocard meets the minimum Pixel Shader requirement, then you might be missing the compiler XBMC needs. Update/reinstall DirectX and see if that resolves the problem.
Control XBMC with Your Android Device
With Google's Android platform catching fire as of late, there's a good chance you either already own an Android device, or plan on getting one soon. That means you'll be able to control your XBMC media center with your smartphone, so long as you install XBMC Remote (download link). This handy app turns your device into a remote control with the look of the Xbox DVD dongle and comes with a ton of features, including the ability to display cover art (when available), sort through your movie library by title, actors, or genre, manage multiple XBMC instances, and a whole lot more.
XBMC Keeps Freezing
On occasion, XBMC seems to go into a coma and becomes completely unresponsive when trying to open up a movie or music file. We've run into this ourselves, but if it happens frequently, it might be indicative of a corrupt database. To fix the problem, navigate to C:\Users\[USERNAME]\AppData\Roaming\XBMC\userdata\Database and delete all the files in this directory, but not the folders.