The answer to your question will depend on a few factors.
If you want to play through every difficulty or want to make sure that you don't inadvertently handicap yourself by choosing poorly, go with a predetermined build. I would recommend the Fishymancer for ease of use and simplicity for beginners.
Otherwise, take solace in forging your own path, but withbearing in mind that you may wind up wasting precious time out of your life if something goes awry. Also remember that you won't ever max out all of your skills. It's best to choose a 'theme' (as most builds already do) and stick to it.
Either way you've made a great decision to play a great game.
Have fun!