Some specs you shld be looking for could be what type of sensors, such as laser,infared which are the more common ones.. Next up would be the additional features of the mouse that you need or not, such as more buttons and wired or wireless..
For DPI, it is dots per inch.. It means how many dots the mouse cursor cover across the area in windows or games when you swipe your mouse.. In literally terms, it is higher the better, but you hands may not be able to handle such high DPI and sensitivity at the start.. I started out with a diamondback 3g at max DPI of 1800, i take awhile to get used to it too, with a sensitivity score of 6,den slowly up to de max of 10.. After that, i upgraded to a deathadder where the max dpi is 3500, i tried 3500 at the start, it is holy crazy sensitive and too fast for my hands and eyes. So i drop to 1800dpi but a higher sensitivity of 8. Once get used to it, i changed to 3500 and now i am using 3500dpi with max sensitivity in games.(i play counterstrike online and L4D2). When my friends try my mouse, they say my sensitivity and movement of the mouse is crazy, they wonder how i control it anyway...
Just for your information, if your mouse is like super high end and good, but u need a mousepad and a good quality one to improve your performance and gameplay skills.. A gaming mouse and regular mouse that is widely available and selling cheap, there are difference with them and you can feel it..
