5 things to remember when buying a tablet.
1. Always check that the firmware used is safe and stable. It is the firmware which makes or breaks the Android build on the tablet.
2. The amount of RAM may or may not matter depending on what Android version you use. So you might have a tablet with 1GB of RAM but if you use one of the earlier versions of Android it wont make much difference from a tablet with 256MB of ram.
3. You will need 3 things to help avoid bricking your tablet for good or losing important files.
a) Root your Tablet
b) Update your Firmware, and be sure to always have a copy your current and previous Firmware on storage cards.
c) Back up your Tablet. This will require you to learn how to root your device.
4. (optional) Regardless of how much free space you have on you tablet, use a storage card for you music, video, images, documents and similar files that aren't necessary for your tablet and its apps to work properly.
5. I consider this the most important one. You get what you pay for.