Like most VNs, the routes are actually quite easy to get and you shouldn't really need any help. Just pick all the choices that involve being nice to or spending time with the target heroine, and that's it. In particular, always follow them whenever they go somewhere if given the choice (no matter how stalker-y it feels). If for some reason you do need help, the "Routes: Walkthrough" section lists what I think are the important choices for each route (and documents how to get all the bad ends).
...