Instarmac Ultra Tile Fix Grout mixes easily with water and is easy to work into the interstices between your tiles. 1kg of grout powder will, when mixed with water, cover an area of approximately 0.75m²  - depending obviously on your tile sizes and the width of the gaps between them. Use around 3 parts powder to 1 part water  and mix until a smooth consistency is achieved, leave to stand for 2 minutes then remix. Do not mix more than can be used in a 30-45 minute period, and don’t re-wet.  It is usual to pick a dark grout to use on areas of dark tiling, and a lighter one alongside light tiles; of course most projects will use a mix of tile tones, and there are middle tones of grout available which work well in these situations.  But remember that dramatic effects can be achieved by using an unexpected shade of grout in a particular context.