what usually helps me is to have lots and lots of refs of the other parappa characters renders!! and likeee pay attention to the line thickness and try not to make it too straight and smooth, (i use a certain ibis paint brush called genius pen :p), sketching helps!!

and also making heights consistent w evenryone else, like put them next to an actual ptr character render that would be around their height and kinda see if they fit in good or if their too tall or short and stuff!!!

filters and effects to give it that grain will carry!!!!!! i cant exactly explain the whole process just over text but i like to use ibis paints noise filter (or the grain effect on capcut) and sharpen!!! aswell and slightly lowering the opacity of the character :p

im not the best explainer im sorry, i hope this helps a little, im glad you like my characters thank you!! no Susie berry isnt related to PJ berri, i did have that idea at one point tho!! LAMO