Now, time for some tips on being a concept artist. I'm quite new to collaborations, but I've already learnt a few things:
Tip 1: Know the story
First thing to have in mind is that the designs must serve the story, not the other way around. Read it all the times you need until you feel like you have a good grasp on the world and characters. Know your genre and the tone of the story. Is is fantasy or sci-fi? Is it more lighthearted or grim horror? You won't design something as simple as a spoon the same way for each case stated above.
Tip 2: Contrast vs Cohesion
Try to put interesting details on each design depending on who owns it and what's used for. Some examples from this project, you can't draw the house of the rich baker the same way you designed the orphanage. Still be careful with pushing it too far, there has to be some cohesion still in the designs of the buildings in the same city. Balancing contrast and cohesion is quite the task, but you can always check some pictures from the real world to help you through. Remember, references are your friends!
Tip 3: Communicate!
Don't be afraid of asking the rest of the team. This is a group project after all, so if you can't really work something out and you need some input on it they'll be the best kind of help you can get. Be it some strange angle on the rooftops or a extra room that just doesn't fit, even if it's the smallest detail, just ask it right away.
In the same way, always be open to change! Maybe you loved a certain detail but it just doesn't work. Then it's time to put it in storage to use it elsewhere. Usually that way things end up looking much better than they first did!
And that was all on my end, hope it could be of some help. See you soon!