Make sure that you go into Safari and close down all the open pages that you aren't actively viewing (by clicking the square/number icon in the lower right corner of the screen). The iPhone is designed to shut down the currently-running app when it runs low on memory, so that the phone app always has enough memory to run. Safari unfortunately takes up a lot of memory for each webpage that's loaded, and large complicated websites take more than others. And Safari can even run in the background, causing other apps to shut down from memory issues. Also, the music player takes up memory itself, that's another thing you can do to try and keep Safari from crashing when visiting memory-intensive websites.
If Safari is crashing to the home screen multiple times in one session, that's a signal that you're system is low on memory; try shutting down the system entirely and then turning it back on to clear out memory. A full shutdown I mean - hold the reset button (not the home button) until you get the option to shut down the system, and then choose that.