ANSWER - I think it depends on how you view witchcraft. My own view is that being a witch is much more about bringing out what is already within than it is putting in what is not already there. So a teacher can be helpful but will only take you so far.They can help you identify which parts of yourself can be developed into practising a craft path but learning witchcraft is different to learning, say an academic subject where the focus is solely on the acquisition of knowledge. A craft path is much more about the knowledge of yourself, practising the self honesty of looking inward to understand your strengths and weaknesses.
That said, there is a lot you can learn from an experienced witch and with the advantage of the internet it is becoming easier and easier to meet people. Forums and Facebook groups are often a good place to start. Don't feel you have to commit to the first group you join, be upfront and acknowledge you are looking for one that sits well with you. Some groups and forums are not designed for teaching so be honest with what it is you are looking for and move on if your needs don't match those of the group. Be aware that there can be a lot of ego in witchcraft and some of the witches advertising teaching (or worse "witch schools") can be in it for the fuelling of their own self esteem rather than a well meaning intention to help. There are some reputable witches on Witchvox who sometimes indicate a willingness to work with newbie witches and this may be a good place to start if your preferred method of study is to work with a teacher.
Beyond that, I'm all in favour of a hands on approach. The best way to get a feel for the craft is to roll up your sleeves and get stuck in. Try something like the Element Encyclopedia of Spells to see some examples of spell work designed by other people. As you get more confident I'd always suggest writing your own work rather than copying anything out of a book but starting with some basic spell books will give you an idea of how magic works and what it can be used to achieve.