How do i make a rena ryuugu cosplay?

Rena ryuuguu is from Higurashi no naku koro ni. I really want to cosplay as her for Sakura-con next year. She looks really fun to cosplay. :C. i just need some guidance on how to make it. My mom is actually going to be the one sewing. She knows the basic skills like patterns, ect, ect. I need information on what patterns she should alter. im pretty sure she knows how to attach the bow onto the dress, but i still want to know that. I also want to know what kind of fabric i should use. (Also, how do i make the hat with the bow on it, ect, ect?? also, how to make the shoe covors and all that) sorry for all the information that i want to know, D: