We are often how to remove scratches and how to clean etc, so here is how we do it.
Most titanium frames are hand finished with a 3M scotchbrite hand pad. These hand pads come in different grades of coarseness and the different grades are easy to pick as they come in different colours. Most titanium frames will be finished with either a dark green 3M pad or like at Reillycycleworks, a maroon pad, code 7447. You can buy these pads online or at any really decent tool shop, car paint suppliers, just google the code.
NOTE: please note this is only for hand-brushed surface only.
If your frame is brushed and in good condition and just needs cleaning then wash with hot soapy water, fairy liquid or similar, rinse with hot water and dry off. Then inspect the frame to see if there are any scratches, if there are then take the 3M pad and rub over the marks, brushing with the grain of the tube and gradually the marks will abrade away, obviously avoid any decals, mirror polishing. Once done and this might sound odd, but it works a treat; take a very clean white cloth and put a small dot of chain lube or similar on the cloth and work into the frame. Any dirt left over will be seen on the cloth and the oil rubbed all over the frame will take out any finger prints/streaks etc. Only a little oil mind you. We always do this on show frames to remove fingerprints when people touch bikes a lot.