It's not a lack of RAM per se, at least not always. There is some crashing (particularly with apps) that are low memory errors, but most Safari crashes on A7 iDevices seem to not have much correlation with high memory usage.
It helps if you:
1. Note websites or actions that crash often, and avoid them if possible.
2. Copy text that you are typing before changing tabs, just in case it crashes or reloads.
3. Avoid scrolling too fast or too abruptly, especially when the page is still loading.
It really is baffling how much we have to go through...