A lollipop stick and a ball-point pen are very handy tools for grouting.  You can use either of them for recessing grouting joints.  You have to do the recessing before the grout dries out though.  Do not use your fingers to wipe off the excess grout - you'll be much better off using a wet piece of cloth.

It is not a good idea to add recesses to a kitchen work top, since bits of food will collect in the recesses, and quickly become unsightly.  Instead, finish the grout so it's flush with the surface of the worktop.

Use a plastic trims to create neat finishes when grouting tiles round external corners including door and window openings.

When laying thin tiles, it's a good idea to remove the plastic tile spacers before applying the grout.  This way the spacers will not show through the grout after it dries.