Common wisdom

Exclusive RV fitting: to correctly determine mass ratio, it is wise to fit only the radial velocity data. There is a very important caveat you must be aware of while doing this: if you try to fit only the mass ratio $q$ while you keep inclination and semi-major axis fixed, you most probably won't obtain a proper solution! The sound policy is to keep the inclination at $90^o$ and release the semi-major axis, where one must recognise the obtained solution for $a$ is in fact $a \sin i$ and not merely $a$, since the RV amplitude (e.g. $K_1$) is:

$$K_1 = \frac{2 \pi a \sin i}{t_0} \left( \frac{q}{q+1} \right).$$