Someone move this to Mapping Discussion or Mapping Techniques because this is not the right place to ask this.
Anyway, sliders like Mayday requires proper understanding of slider velocity (the speed of sliderball and the length of the slider), 2B and autofail (2B is "stupid" in Chinese, mainly because of how "stupid" it is when playing(!); autofail is the most common glitch happened in 2B mostly), multiplying/dividing BPM, slider patterns, and much more.
Personally, based on the amount of maps you made, I don't think you have learnt enough fundamentals to reach this. Just map and improve more.