I've never done a composition sketch before, so I'm not sure if I did it right. But hey, that's why I'm here, right? xD
It's a good sketch and a good start!
The first two things I want to talk about is
flow and
the rule of thirds.
The flow of your image is how your eye moves around the image. You want everyone to flow in an intentional direction, but it doesn't mean that ever single object must end up pointing towards the subject. It's more of you don't notice it if it's done right, but you DO notice it if it's in the way.
The shubbery is mostly pointing away from the frog, which can be ok at time to frame him, but right now, it's just pushing your eye to the left and into a dead space.
The second thing is the rule of thirds. I'm sure there's some fancy math behind it, but in general if you divide your image up into 3rd sections, the 4 points where they meet are visual "high" points. It's just pleasing to see them in that spot, pulls them into focus more, and just helps organize your image. Not all images have to follow this, but it can help!
There are two different options I can note here. The frog doesn't have to be so on the rule of thirds, if he is infact, reclining back and observing the world. Which is fine, you just need a few more things going on in the background! However, the image can also be interpreted as this is the frog, and this is HIS swamp. In this case, he needs to be a little more upfront and important.
In both of them, I moved elements around to either let them be more focused, or pushed more into the background. I also lightened the base color of the frog to make him show up a little more. This may be done by knowing that he'll be more patterned than the rest, but for now I want it to show clearly.
These are just quick, sketchy thoughts on your composition! Any changes you want to do are all up to you, but I'm trying to give you visual examples of what I want you to take into consideration with a composition. Just try to separate the elements and play around with their positions! It's hard to teach that part without first having something to start on with as a base, so that's why I've asked everyone to just draw something first before we go into it.
While we're waiting on everyone else, I'd like to see a refined composition sketch, but it's not going to be required. We're not going to be going for a final image for this class, as that takes time and it's less me teaching you, but just doing something. It's hard to have critique when you're already done with it!
But either the version you have now, or if you choose to revise it, I encourage you to finish it if you like it. : )