How can I practice writing to have a pen?

First of all, according to your practice habits and the size of your palm, choose a brush of appropriate size, which must be authentic wolf hair or wool. Furthermore, it's best to insist on writing with your elbow hanging. I feel uncomfortable at first, my hands are sore and my arms hurt. But after a month, you will find that your arms are much stronger, plus a good writing brush and a correct writing style, writing with a pen will not be a problem.