I made a guide for planning and landscaping a long time ago on my tumblr, but I need to update it. Basically how I plan my towns is like this:
I decide on how many player characters I want to have and what villagers I want (dream villagers if you will). Next I move all of my flowers to the beach and cut down all of the trees (give myself a blank slate). Now I use paths, but even if you are going for a natural forest look I still suggest doing this, I start connecting things with paths. I start with things like town hall, the plaza, retail, train station, character houses, and I play attention to paths that I take normally when walking around. I plan spaces for villagers, characters, PWP, other buildings such as the police station and cafe if I'm going to include them, etc until I have paths that work for me. If you're not hacking, start hoarding tree saplings and bush starts as soon as you get the flower shop because after I get my paths set up how I want, I start landscaping around them and around houses and buildings and basically work on one area at a time. If ever I get tired of landscaping, I work on houses. I usually think about what themes I want in rooms to begin with, how many expansions I want, and then I look through all of the furniture
here and make a list of all the things I want for the character. (I usually hack them in now, but it can also just help you know what to collect from shops). And with the welcome amiibo update it's super easy to move all your stuff around so I just usually dump a bunch of stuff in the room then move it around until I'm happy. And I just keep working like that until I develop my town how I want it. If you don't want to use paths you can kick up the ones you laid down to begin with so that things look more natural, but you still have kind of a clear direction of how to navigate the town. Hopefully this helped!