If its the ipad first gen, there's not much you can do. The low amount of RAM in the ipad is what causes the problem.
Make sure you have closed any background apps by double clicking the home button and touching one of the icons that pop up along the bottom until they start to wiggle and a red minus shows up in the top right corner. touch the red minus to close the app.
This might help but you will still have crashes from resource heavy apps like facebook as well as certain web pages.