After reading various DIY cleanup instructions, I decided to undertake this project myself...this is after collecting 4+ years of nicks and scratches on my watch. I hadn't realized that titanium was relatively soft in spite of it's strength.
Tool: Old (newly retired nail buffer...shhhh...don't tell my wife)
Process: I have read about using a pencil eraser, but the scratches and nicks are a little more severe...so I decided to promote an old 6 'stage' (finger)nail buffer. Not knowing what grit (roughness) to use, I started with the smoothness and worked my way up till I noticed that the imperfections started to buff off....since the going was slow, I went 1 rougher so I could buff of the deeper blemishes. I then went to one smoother to achieve a similar original matte finish. Make sure to sand/buff in a consistent direction.
Couple of macro shots of the Bezel on a 3+ year old Tissot Touch Titanium....before:
Looks like this still needs a little more touching up:
Another quite badly scuffed up part of the bezel:
It took me buying a second watch to muster up enough courage to undertake this project. I was afraid that I would totally botch up the finish. I'm very pleased at how this little effort made such a big difference.