Just a little disclaimer here... These are my personal favorite methods. If you find something else that works better for you, I encourage you to use it.
Hi Zero sir, i haven't tried using alcohol dis-infectant for acrylic paints.... does this method only apply for tamiya using handbrush methods? i wonder can apply to airbrush using alcohol, does the result same? just curios i mean... 
As a rule, the alcohol works best for thinning Tamiya acrylics. I haven't tried it with Mr. Color, but I can tell you that works with Model Master and PolyScale paints--just not quite as well. It tends to make those paints "chunky" in the paint tray after a short while, so water tends to work better with those. For Mr. Color, I'd recommend Mr. Color thinners.
Zero:
Ok one more question do you put a gloss top coat over everything like FFA/91% Alcohol or Mr. Topcoat for a gloss I was just wondering or is just simply the Tamiya paint?
When using water-slide decals (like the Bandai aftermarket decals), you need to have a glossy surface for them to adhere to. So the rule is to (1) paint (2) apply gloss (3) apply water-slide decals, (4) apply decal softener/setter, and then (5) apply matte. Up until recently, I've just been using "rattle cans" of Testors "Gloss Cote" for the gloss lacquer. And that works fine. More recently--based on a tip from another modeler, I've just been brushing a little bit of FFA directly on the area where the decal is to be applied. This works equally well.
Again, use what method is going to work best for you. By hand-brushing the FFA, I don't have to spray on the Gloss Cote, so it's a savings of time, drying time, air quality, and effort. That's what works best for me.
