I have the similar situation of another poster, but my question is a bit different.
I am installing 12 by 12 porcelain tiles and want to cut around the front curve of the tub.
Other than eye balling it and then cutting, is there a technique that can be used to accurately approximate that curve before I cut it?

Your best bet is probably something called a flexible curve. Should be able to find at home center. As you can see from the dust on mine it is very old and the place where I purchased it is no longer in business.

Another approach would be to lay a piece of wood such as 1/4" luan next to the tub and using a set of dividers scribe the shape of thew tub on to the wood. Cut this templet out. Put this on another piece of luan and with the dividers reversed scribe line that would be the profile of the tub. Don't change the setting of the dividers. The reason for having to do it twice is that while the first templet will be the same shape, its dimensions will be different. After getting the shape correct cut off the straight edge so that the templet will fit between the last row of tiles and the tub. Line up all of you tiles in a row, place you templet over them and mark the tiles.

Harold's approach is certainly a good one. You know you can just make a template from a piece of paper too. The paper is ultra flexible and you just tape it to the adjoining tile with edges matching, force the paper up against the tub and scribe the crease with a pencil. The harder part is cutting that curve in porcelain. I use a wet saw and make many cuts into the curve like I am making tines on a fork. Make the tine as large as the space between the tines, they will all snap off with almost no force, use a ceramic file to remove the edge.

I have done with old cardboard boxes. Cut the boxes the same size as your tile, use the spacers as well and lay out the whole curved area, then # your pieces and lay out the tiles. I cut the tile the same way ballengerb1 explained to you. I smooth most of the tile with the running blade before I use the file... However if this is your first project I would just use the file... Fingers are nice to keep around.
Mike

I agree with the first timer advice, I'm down to 7 fingers so I want to keep what's left.