Like previous games in the series, Life is Strange: True Colors will regularly present you with choices that will influence the outcome of the story. Most of these choices are mandatory but a few are optional and easily missable. Below, we go over all the choices that are important to True Colors Chapter 1: Side A. You'll make additional decisions beyond these ones, but they don't have as significant an impact.
As an additional note, though we don't go into detail about all of them here (we'll cover the major ones), there are certain choices that can influence how Alex perceives herself. Notably, whether she loves music and herself. If you constantly make decisions that have Alex look down upon her incredible musical talent, she won't as easily regard making music as a career choice. Additionally, folks around Alex--upon learning of her Empathy--will regard her as a superhero, but it's up to you to decide whether she ultimately views her abilities as a gift or a curse.
Personally, we advise you to go for a hug. Neither choice has massive ramifications for the story (at least as far as we can tell) but hugging Gabe as opposed to shaking his hand will influence the two siblings' relationship to start on as positive a note as possible.
If you want to ensure your relationship with Gabe is as close as it can be, side with him. However, it's better to side with Riley in this debate as doing so will ensure you set the most positive first impression you can with her (similar to hugging Gabe at the start as opposed to shaking his hand). Being Riley's friend and someone she can trust will be important for later chapters.
It may seem like the right and responsible thing to do to tell your brother that his adopted son is planning to go visit a mine after dark. But that's how cops think, and Alex ain't no snitch.
And beyond that: Your choice in this instance doesn't really matter--the overall story won't change depending on whether you blab or keep your mouth shut. But you do get brownie points with Ethan for keeping his secret and that's more important.
Don't be a coward.
In order to set a positive first impression with Charlotte, it's important to be positive or ambivalent about how Alex feels about Haven.
In this instance, telling the truth and then impressing Jed with your performance is the best course of action. As a server, you'll need to clear the backroom, take and remember two orders, and check in with people. The only tricky part of this is remembering Diane and Duckie's orders. They will tell you what they want and then you need to tell Jed via a multiple-choice test. As soon as you get their order, just go straight to Jed before you forget. You'll have time to do everything else afterwards.
Frankly, it doesn't matter whether you win or lose. The important thing is to play so that you start a friendship with Steph and establish a repertoire that can lead to romance down the line, if you so wish.
Though you do earn Mac's trust by covering for him, the dude doesn't deserve it. And even without his trust, you'll be able to get the information you need from him later (it will just require a little push on your part). Tell Riley the truth--it will end her relationship with Mac for good, but it will further cement your friendship with her. More importantly, you'll firmly earn her trust and you will need that for later.
There is no wrong answer here--either choice will improve the relationship between Alex and Gabe as her opening up to him will prove to him that she trusts him. However, there is a branch in the story here. If you tell Gabe about your powers, he will be the first to know about them. Continuing to hide them means that someone else (one of True Colors' two romance options--Ryan) will be the first to know, ensuring that their relationship with you will be a lot closer (as they will then become the first and only person to know).
This may make it seem like hiding your powers from Gabe is the way to go, especially if you want to romance Ryan, however, telling Gabe about your powers is extraordinarily helpful in getting Alex onto the track of regarding her abilities as more of a superpower than a curse. You'll be able to get her on this track regardless of what you decide here, but if you want that process to start sooner rather than later, confide in Gabe.
You want to tell him "red wire" as that's the correct answer, further solidifying Alex as a trustworthy person in Ryan's eyes. You'll need his trust if you want True Colors' "good" ending.