To open up most devices, you will need a tool that is:
- fine enough to fit into the gap between the different parts of the case of your device.
- long enough to provide you with some leverage.
- flexible to pop clips without breaking them.
- soft to not leave any marks.
A steel screwdriver will damage your device, so it is much better to use a plastic tool.
Some people use a credit card, a guitar pick, or even their own fingernails. And while this may work for some devices (such as those using the Q88 case), it will not work well for most.
Buy your tools
You buy a set of tools for this. Search your favourite online auction site or your favourite chinese shopping site for "tablet opening tools". This tends to cost at least 10EUR and will probably mean that you will have to wait for 2 weeks for it to arrive.
Make your tools
It is very easy to make your own plastic tool. Just find an old toothbrush and cut off the head (the part with the bristles). You then need to work down the stump so that it goes roughly in the shape of a flat head screwdriver. This is easiest with a fine file. Use some fine sandpaper to finish it off.
The great thing is that a toothbrush has a lot of flex. This protected your gums, but it will now protect your clips instead. Also, if you damage the head of the newly made tool, you simply file off another bit.
Various household items
Some have claimed success using a guitar pick, some have used smart cards like credit cards. Also edges of clear plastic packaging (< 1mm thick), as commonly used in packaging electronic components and accessories. (Your mileage might vary, as this might not give you either the pointy edge required or have enough leverage.
The New Device Howto explains how to get serial, but also mentions disassembling your device.