Lately it seems that apps tend to crash a lot on my first-generation iPad. Safari is one of the biggest offenders, and it appears the problem is at least partly from lack of free memory. If Safari starts crashing everytime you open it, it sometimes helps to close all apps in the multitasking bar.
Double-click the Home button to bring up the multi-tasking bar at the bottom of the screen. It contains all the applications you've had open recently. You may be astonished at how many are there.
Press and hold one of the icons in the multi-tasking bar until all the icons in the bar start wiggling. Click on the "close" symbol on each in turn until all are closed.
It is also a good idea to restart the device. To do this press and hold the wake/sleep button at the top of the iPad.
And finally, keeping the iPad plugged in while using it seems to help immensely as well.