First of all, we should practice from the basic strokes and gradually improve to five links: radical, frame structure, composition and layout, and unique techniques. Secondly, read and analyze other people's works and practice records, analyze their own problems, and constantly improve. Thirdly, we should pay attention to three writing skills: strokes, structure and composition, which are the key to writing well. Finally, we should communicate more, ask people who are better than ourselves and absorb their skills and methods of practicing Chinese characters.
If it is purely practical, you can choose a gel pen with a refill of 0.7 or 0.5. 0.7 refill, the words written are clearer and thicker, which is generally used for taking notes, signing, etc. 0.5 refill is relatively thin, generally used to write small characters, such as horizontal grid writing (more horizontal grids, narrower grids). When writing in a relatively small grid, you can only use this 0.5 refill, because the thick refill is easy to blur and the lines are easy to stick.
If you want to practice hard pen calligraphy systematically, then at this time, you'd better prepare a gel pen with a slightly thicker refill of 1.0. This kind of refill is suitable for writing large characters, with thick strokes and thick, dignified and clear lines, and is suitable for showing the effect of change, pause and gradual change of stroke thickness.