Apple has set up the iPad to be a very accurate RAM management tool; you very rarely need to worry about RAM (especially on the newer devices, especially) because it will free up RAM is it needs it to run.
However, you can free up some yourself by closing the active apps within your multi-task bar. Doing that will manually free up some RAM. In addition, turning the iPad off, then on every now and then will help the iPad keep itself sorted.
But again, unless you've got a specific crashing issue, IMHO, it's best to let the iPad handle RAM. It's how it was designed.
Marilyn