With the tires, invest in a bag of cotton balls for removing make up.
Stuff the tires with enough cotton so they "fill out" and grip the rims of the wheels. You should be able to avoid using glue.
Spray painting takes practice.
ALWAYS make sure you clean any contamination off the plastic before you spray. Warm water and dish detergent for greasy dishes might work. A weak solvent or rubbing alcohol is another alternative. Your finger prints can be enough to cause the paint to act weird.
In most cases, spray several light coats then follow up with a thicker final coat. This is one of those times where less is almost always better.
If you use enamel paint, give the paint on the body at least one week to fully cure. Enamel produces a gas as it dries and cures, any clear coats applied over enamel WILL bubble if the enamel isn't done "out gassing".
Once the paint has fully cured on the body, you aren't out the woods yet.
That shiny paint you laid down might not be so shiny after the paint fully dries. DON'T PANIC! Invest in some Tamiya mild polishing compound and an old (but clean) cotton tee shirt. Spend a couple of days lightly polishing and buffing the paint.
Take your time and you WILL be rewarded.
Clear coats-. I avoid them like the plague. I have yet to find a clear coat that doesn't yellow or brown out after about one year.
There are folks on YouTube who
still use acrylic floor finish on their bodies. It looks great on the video and its super simple to apply. It doesn't look so great after a couple of months.
Paint brands and types-. This is really at your discretion.
Use what you can find. If it comes down to using a spray can or an airbrush, both have their limitations. Enamels in an air brush means you'll be spending at least as much time cleaning your air brush than you did putting down the paint.
Tamiya has an excellent range of spray lacquers and "hybrid" enamels. The only downside is that they aim for "one shade fits all" colors, so what you get will usually look great- it just might not be accurate.
If you aren't sure about using spray cans, buy two cans and use one to build up your experience level on some scrap plastic.