Airbrushing is a process with lots of variables. I think it is good to elimate as many of those as possible, especially when new and learning.
Using mineral spirits of an unknown nature (no two have much in common, from what I've read over the years), IMO is a variable you do not want. I'd advise getting hold of a jar of Humbrol enamel thinner, and sticking with manufacturers own thinners for your airbrushing at least until you have a basic feel for the process.
Good luck to you, congrats on your initial post, and welcome to the forum.