Odds are you've forgotten what some of the cursive letters look like since grade school.  Seek out some of the many cursive practice books that have lines on the paper to help you practice making the cursive letters.  There is more than one style of cursive, of course, and it is fine to give your cursive an individual flare, as long as it is still legible.  But it's probably best to start out by copying an existing style. Seek out websites with study tutorials and printable practice sheets.  Some even have animations of the pen strokes used to make each letter. Most people write by manipulating their fingers, what is called by some “drawing” the letters.  Handwriting artists utilize their arms and shoulders as they write, which facilitates a better flow and thus less angular, choppy handwriting.   Try “air writing.”  You may feel silly doing it, but it will help re-train your muscles. Pretend you are writing large letters on a chalkboard.  (In fact, you can practice writing on a chalkboard.)  You will naturally use shoulder rotation and forearm movement to construct your letters. As you become more proficient at air writing, reduce the size of your invisible letters and assume the positioning you would take to put pen to paper.  But continue to focus on using your shoulder and arm, not your fingers. The two essential moves in cursive handwriting are the upsweep and the curve, so practice them first before writing full letters.  You'll want your practice stokes and eventually your letters to be evenly spaced, so lined paper will be really useful here. If you want to write on a blank piece of paper, put in light, evenly spaced pencil lines with a ruler and erase the lines once you've written your letters. To practice the upsweep, start the pen just above the baseline, brush against the baseline as you pull down and slightly forward, then turn the curve upward into a straight line (angled slightly forward) through the midline and to the topline. The basic curve practice stroke resembles a lowercase “c.”  Start...

TL;DR in Chinese:
学习手写体的写法。 用整个手臂去书写。 练习基本的手写体笔画。 开始的时候慢慢写。