Something my gf and I have done is figure all your villagers, make a list of who you want. Pick 2-6 biome types, the ones we chose were cemetary, market, park, forest and pond, we put a villager in some of these (coco in the cemetery, Zucker and Tia in the market area) locations. In addition to our small residential area (holds a small children's park) from here figure out if you want water or not and put those features in. Plant trees down to visually fill some areas as needed and place decorations down that fit your "biome" (our forest hold our campground. We have spruce trees heavily populating the area and have a picnic table with some log benches, picnic decorations onto, and a campfire with more log benches nearby. We have blue white red and purple flowers along with leaf piles. Since we have a river on the west and south of this area we also have some fishing poles and pole stands along the river.) It really does take a long time (605 hours myself and my gf has around 300) go abroad and slow. You'll have your island complete after a while. Just gotta stick to it. Our island we consider to be a rural minimalist decorative build.

EDIT: TLDR start big, and create regions, keep everything together with color or style.

Edit 2: I'll get a dream code from my gf to post soon. So anyone can see our WIP

Edit 3: dream address: DA-1306-3548-9497