In the Long Run, Classes Don't Matter

Don't sweat your initial class decision. A starting class in Dark Souls is simply a package of preliminary attributes and equipment. If you decide you want to transition into a heavily armored tank from a robe wearing mage, you absolutely can.

On your first run through the game, if you find that your chosen starting playstyle isn’t working well, change it! You can always go for a more focused build on later characters once you have a better understanding of the options at your disposal. Playing a “jack of all trades” with your first character is a good way to learn!