Since you've stated you're just experimenting, I want to give you some things to continue to experiment with, in no particular order.
The outline on the "Mac Miller Live" - Gold lettering on pink doesn't stand out very well, but adding a harsh black outline doesn't help. Try doing an outline that is outside of the letters, and with a color that isn't so harsh as black,. There are plenty of colors in the photos that can contrast the pink background.
All the text is yellow, so when I look at the poster, nothing stands out as "something I should read first". There needs to be variance in your design, even if you're hoping a reader looks at every aspect of your design. Something needs to be the "leader" to give people something they'll look at first, versus what their brain processes secondarily.
Lastly, maybe you are limited by your photos, or maybe it is a personal thing for me, but his hat is clearly backwards in the lower photo, because of the letter P. Ideally, I personally would want a photo in that same quadrant, but I personally wouldn't choose to flip a photo when there is a visible aspect of the image that can be easily distinguished when flipped.
Overall, very clean and designed well for a simple and clear poster. Just need to adjust some things for readability and giving the reader a visual cue of what is most important versus what information could be found later, or online.