Two of the most vital things that need improving from first look:
The second image of the first gig link has a spelling mistake on the word “Thumbnail”. When advertising work of this nature, it’s really key to make sure that spelling mistakes are not present in the work.
The pricing seems fair but consider running your services for much cheaper to begin with in order to build up a client base. Youtube thumbnails are going to be required by your customers more than one time, therefore getting clients into your work flow is key and hopefully they will return business.
If you want more thoughts you can contact me via message, keep up the good work though, im new here too and looking forward to being part of the community.