First of all, you have to think about your needs. Do you need one which will work greatly for communication? Are you looking for one that can be used for entertainment like listening to music, playing video games and the likes? Will it be an aid for the things that you need to job for the office? Or is at all of the above? When you have decided what are the things that you want for your gadget then you can start eliminating those which will not provide you with your needs.
Second, specify your budget. If you skip this part, you just might end up using your credit card, swiping the amount of the gadget, only to realize a day after that you spent far too much than what you can afford. So, before you even set your eyes on a gadget, it is best to specify how much you can spend.
Third, do extensive research first. Just think that the internet is always there to provide you answers so might as well use it to your advantage. Look into the specifications to ensure that it will be able to work with your needs. Also, you definitely have to check out the comments and feedback from other people who have tried using it too.