Even though I love doing this, I have a hard time depending on what it is because the shape of my erect dick goes up and away from my body. I always wanted it to put it on my lower gut and have it roll down my body and cover my cock, but it doesn't always work especially with things like yogurt, and all of the gunge usually misses my dick and just goes down. How do I make this better? Do I just pour it directly on my penis?

Yes, pour directly on your dick, or wear tight enough shorts that they hold the messy and cover your dick that way.