A brief introduction: children (under ten years old) had better start learning regular script. You can choose Yan Zhenqing regular script and Liu Gongquan regular script for copybooks. Teenagers (below 18) can learn official script, regular script or running script. The copybooks are Ou Yangxun's Jiuchenggong Liquan Monument, Zhao Mengfu's Danba Monument, Yan Zhenqing's Magu Mountain Xiantan, Yanshi Temple Monument, Liu Gongquan's Shence Army Monument and Chu Suiliang's Yin Fu Classic. If you are young and middle-aged, it depends on what copybook you like. This choice is wider. If you are a beginner, you'd better start practicing from official script, so that you can get on the road faster. For the elderly, official script and regular script can be used quickly. Ou Yangxun's Inscription of Liquan in Jiucheng Palace is more appropriate.
I hope I can help you a little.