i don't have experience in the kind of intricate dresses seen in lolita fashion, but i do make and sometimes draft clothes. knowing your body measurements is super important with making anything, that tends to be where all the math and numbers come in. there's unfortunately no getting around the math lol. having a sewing machine definitely speeds things up, especially when it comes to making and attaching ruffles, but if you don't have one, you can definitely do it by hand with a lot of patience. because lolita's defining feature is ruffles, you're gonna need a lot of fabric if you want to make skirts.
i think
a skirt like this could work for lolita? circle skirts require a bit of math, but they're really simple to make. in the video, she uses a serger to finish off the edge of the long strip of fabric that's going to be the ruffle so the edge doesn't fray, but since i'm assuming you don't have one, i recommend you fold it over twice like half an inch and then sew that down. that's going to be the hem.
this shows you how to gather fabric for ruffles by hand. make sure to do that running stitch and gathering not on the hem.
for making a bodice to attach skirts to, look into bodice block tutorials. it's a ton of work but it's so worth it because then you'll have a base to work with whenever you want to make a top.
idk what else to add, but if you have any questions feel free to dm me ^^