** the player's prowess in the specific skill that is used for improving the item
** the quality of the materials that are needed for improving
*Sweet spot improving is a method of imping quality way over your skill level and that gives double the skill gain on top of [[Sleep bonus|Sleep Bonus]] and other skill gain bonuses. The formula to find where sweet spot ql starts at is x*0.77+23. [https://www.google.com/search?sxsrf=ACYBGNTMXRfP4Pihid07k6Jh5zLe7CjnTg%3A1581104356588&ei=5Lw9XoO4I8nimwWkypmwAg&q=x*0.77%2B23+from+0+to+100&oq=x*0.77%2B23+from+0+to+100&gs_l=psy-ab.3..35i302i39.89317 LINK] to graph to visually find it quickly for your skill (X is your skill and Y is the quality you need to improve over)
== Tools ==