Welcome!
Start with a basic kit that is one color, a Russian T-34 is a good simple tank that is usually just 1 color, Russian green. For the cost of one jar of hobby paint buy a can of Testor's Dark green in a rattle can.
Now before commiting paint to the model practice spraying something else. I like to 'test spray' a piece of wood and if it lays flat & shows the detail its ok for a model. A few light coats is better than 1 heavy coat.
*Not all rattle cans are created equal! If globs or lumps come out delegate that can to another use. Shake well, start spraying before the model & move smoothly across without stopping and stop spraying past the model. Hold approximately 6" away at a 90 degree angle.
With rattle cans over spray is unavoidable, leave details like tools off until base coat is on. Rubber tires will need to be brush painted & I recommend painting them before fastening to the model. The tracks can be a steel / rust / mud mix so paint them separate as well.
Now for the kit I recommend Tamiya's vintage T-34/76 M1943 kit # 59. The parts count is low as is the price, has a good fit & easy assembly with 'rubber band' style tracks. AVOID individual link tracks for your first build or two. The kit can be improved but that is not needed for your first model, OOB is just fine. (OOB = Out Of Box)
After you have a few COMPLETED models built then ponder if a airbrush suits your needs, many award winning models are painted with rattle cans. I am a rattle can modeler as I tend to get more satisfaction out of the build & scratch building than toiling with the painting process.
I could go on but the important thing is to have fun! Each model completed will gain experience & skill.