For the most part, there isn't really a need for a guide since you'll get on whichever path you want naturally. Major choices also tend to be emphasized as well, such as one that says it'll be the most important decision of your life.
If it helps though, the first split is whether you choose to accept or reject Caijoru's offer. If you accept his offer then it splits into Daren's and Ted's routes on Day 7.
If you've been spending time with Ted, then you'll be on Ted's route. If you've been spending time with Daren, then you'll be on Daren's route. If you've been spending time with both, then you'll be given an option between the two on Day 7. The only exception is that if you've told Ted you have feelings for him, then you will be guaranteed to be on Ted's route in this path.
From there, both routes split into multiple endings. The choices for which ending you get are made obvious when you get there. The only change is that one of Ted's endings changes slightly depending on whether or not you've said you have feelings for him.
Now, backing up a bit. If you rejected Caijoru's offer, then you eventually get an option for who's route you want. This is also made obvious when you get there. None of the routes on this path are finished just yet.
As far as other choices throughout the vn go, they do not affect which route/ending you get. If something does look like it would make an obvious impact on the ending, then it won't. These choices are there are flavor and only affect small bits and pieces here and there. An example is that if you order pancakes at the diner, then later on into the story, Daren will buy you pancakes because he knows you like them. Every single choice you are given will have at least some sort of change later, even if it's small.