A small gloss roller is best then you don't get the brush marks. To avoid getting paint on te grout make sure you do not overload the roller wth paint and if you do not have a steady hand, then use a paint guard.

Quite agree with 'Chapman Fencing' However if you insist on painting the floor tiles you must make sure of a few things 1. the floor must be really clean, no oils or wax residues, best cleaned with strong sugar soap then rinsed with plenty of clean water. 2. Floor must be completly dry. 3. A '2 pack' paint would be best a tile paint from a DIY store is no good at all. Good luck !

Hi , Using a roller will be more efficent because it will use less paint in one go and the layers will dry quicker.
also there will be no brush lines.
dryplast.

Please do not paint your floor tiles the chances of getting the paint to stay on the tiles is remote and the chances of it looking nice are even more remote. I would suggest you either save up and, replace the tiles or buy a big rug.

if you dont want to get into the grout it will be difficult to do with a roller its sounds like a very tedious job with a small brush that way you are sure not to get it into grout and yes you can get speicial tile paint malc.

BEDEC DOES A MULTISURFACE PAINT THAT WORKS WELL WITH TILES IN USUALLY ONE COAT. RE THE GROUT, IF YOU HAVE THE TIME TO CUT IN AROUND INDIVIDUAL TILES,THEN GREAT, IF NOT, WE RECOMMEND THAT YOU RAKE OUT THE GROUT THERE AND RE-GROUT AFTER YOU HAVE PAINTED FOR A PERFECT FINISH, THERE IS NO QUICK SOLUTION IM AFRAID.

Painting floor tiles is a no no
Don't be a cheapskate.
For what it costs I would put new tiles down first