Something that came up in the first brief playtest of the system is the idea of Helpful Actions. In short, an action that someone can do in preparation for a follow-up action, or an action someone else takes, to give you advantages on your roll. The action itself is pretty straightforward denoting that in step A, defining your action, you declare a number of advantages you want to try and give yourself on an immediately following action or an action someone else is attempting. Increasing the number of advantages you want to give or receive increases the difficulty for each advantage after the first.

Broadly, I think this is all well and good and helps keep everyone engaged with the moment considering if there's anything they can do to help increase someone's chances of success or ability to take on more relative disadvantages to increase their effectiveness. My only reservations have to do with whether or not, moment to moment, this would be overused or get out of hand. Imagine if every player for every action wanted to make a "Helpful Action." It could get pretty busy.

Here are two tentative solutions to explore if you decide to allow "Helpful Actions." 
1. The first is very simple: You can only receive Advantages from one Helpful Action whether that be an action you took in preparation or an action someone else is taking to support you. This is cut and dry with no ambiguity.
2. Assuming any given encounter has some loose initiative-like structure to it, allow each player to have an action they can only take on their turn as well as a second action they can take any time during the round. This could be to attempt to give an opponent a disadvantage to an action they're attempting or provide advantages to an ally for something they're about to attempt.

These are not mutually exclusive and perhaps both can and should be true. This addition feels very promising and will likely make it into a future update of the rules.