Favourite character for the begin?

As a new player i would start by playing support, that way you can have an understanding of the game and will not get as punished as you would if you were playing a solo lane, another lane you can practice is jungle, since its a crucial role for your team and will help you out learning paths, objectives and map awareness, knowing when to gank, when to step aside and when to just leave it be and get back. A good champion to start as support would be soraka, sona, nami and yuumi, all of them have decent cc and help you out with healing in case you go to far and get punished, it will offer you and your ADC some sustain.
As for junglers, a few ez picks to start would be fast clears and useful ganks, i would try rammus, amumu, warwick since both have decent clears and decent cc for ganks.
In the end its up to you if you like them and if you enjoy playing them.