The first one looks great, it just needs to be a little lighter on the right side. The shadow on the right nostril shouldn't be that dark. One tip I like to do is squint at the reference and my drawing to see if the values are similar.
Don't forget the nostrils need to be on the bottom line. They're creeping up on the last two.
Be careful when using the stump because it'll start to look blotchy like it does for the last two. When blending a larger area it's better to use a paper or tissue and save the stump for smaller details.
It might be good to look up blending techniques on YouTube or Google. Try to get in the habit of doing your own research, using multiple sources of information, and never stop learning.