Best way really is to use a grouting float pushing it down as best you can and cleaning away as much as possible off the tiles as you go. Then leave it to dry for possibly 5-10 minutes and then go over it with a damp, but not to wet, sponge. Then leave it to dry again until you can only just rub it off the tiles and then go over it with a dry cloth going 45 degrees to the joints so as not to rub this out. The drying times all depends on obviously how warm the room is.
Regarding the siliconing you can spend a bit of time putting masking tape along both sides of where you want to seal and then after you have gone along it pull the tape off straight away. Either that or you can buy tools to create a better finish but you have to clean the excess silicone of the tool as you go along.