If masking tape tears or pulls off flakes of paint when you remove it, use a hairdryer to heat and soften the adhesive.
#FastTipTuesday - To paint or not to paint!
There's no reason that your garage floor should look anything less than showroom condition!
When it's a normal cement surface - make sure the cement isn't friable or you'll not be able to paint it. For smooth steel floated floors first wash the surface to remove oiliness, dirt and grime.
Use Prominent Multi-Surface Etch Cleaner diluted 1:1 with water using a hard bristle broom and allow etching for 1 hour before rinsing with clean water.
Allow the surface to dry properly for a week. Then apply Prominent 2 Pack Floor Epoxy, 2 Pack Polyurethane or Prominent Stoep enamel in the colour of your choice.
Remember to ask for product data sheets so you have all the important information on surface preparation and application before you start.