I'm working on the two Achievements Stormy Skies and Blue Skies, both double for either the good or bad Ending too. For now I try to get the perfect good Ending, I have most choices locked down but some remain kinda subjective or are missing information in the game itself.

Obviously it only counts after the Gender choice.

Good Route:
Confident:
1 - Bot - Nervously Grinning whenever she looked into my direction.
2 - Top - I boomed confidently.
3 - Top - Guess.
Shy:
1 - Top - Trying to avoid eye contact with her.
2 - Bot - I squeaked.
3 - Bot - Succumb.

3 is obviously still hard but I think you would rather make a playful guess if you are confident and be honest if you are nervous to not embarrass you even more.

4 is a special choice in my opinion, both are rather neutral, which makes them neutral positive or negative. You could either:
4 - Top - I've got a feeling it could be left next? (A suggestion which most likely is neutral even if she is dubious and turns right later)
4 - Bot - I left her to it though as I didn't mind where we are, I was enjoying her company. (You do nothing but she gets frustrated as you say nothing. This could be a little bit more negative.)
As you notice, its really vague to find out which one is positive and which one is negative.

5 - Top - Scour the floor for it. (A rather obvious choice for positive, the other option lets you look like an ♥♥♥♥♥♥♥.)

6 - Top - Hell Yeah! (obvious, its her favorite drink and you would be an idiot to deny that.)

7 - Top - but soldiered through as to not lose face. (Obvious choice, she offers you to try her drink she loves, why would you decline.)

8 - Bot - It is indeed! (shows your interest in sea creatures, which you got a tattoo of and you acknowledge that she saw it.)

9 - Top - It's part of the human psyche, something that can't be helped.
9 - Bot - Just because somebody gravitates more easily towards a certain behaviour doesn't make it right. (<- this one)
I connect this to the question later about if humanity can change. Thought a lot about it, in the light of moral Bot should be the correct answer.

10 - Top - Yes. (Obviously would you be there even if she doesn't care about you, because you want to show her that humans can be different. This basicly creates the bond between her and the character. Every girl, every human likes it if you sacrifice yourself to be there for you.)

11 - Bot - No. (Because we are listening to her and therefore don't notice it at the first try.)

12 - Bot - I disagree. (Because we believe that there will be harmony even if that might not be the case in real life.)

13 - Top - Meekly do as you're told. (Because we are flustered by her beauty and it would look arrogant to get a headstart. It makes more sense to let the race start during the walking to the ocean. It actually is a hard choice because we have no reaction from her, its a shot into the blue... .)

14 - Top - Of course! (Obviously we follow her into the cave we found.)

15 - Top - Oh, and you believe the Rest? (Obviously a teasing question. the other choice nets you the Darwin achievement and is negative.)

I didn't trigger any of the achievements yet but wanted to share my thoughts.
I will update the guide once I found them. If you pick something else please tell us/me and we discuss it.

For the Bad Ending just pick the other choices to knock her off. even if the first 3-4 choices aren't correct you get the good or bad ending.

Disclaimer: I don't own the picture or anything, just found it cute and had no other picture.