As has been discussed here many times (and can be found via searching), open carry is legal in MA. However, given that MA has discretionary licensing, most of us do not recommend open carry, and recommend that you use proper concealment.
There are many ways different ways to carry concealed, from pocket carry, to "smart carry" holsters, to IWB, to OWB, cross-draw, shoulder holster, etc. All have advantages and disadvantages.
As for cover garments, you can wear a polo shirt, an open shirt, a photographer's vest, etc. Heavier, thicker, darker garments will typically conceal better than thinner, lighter garments.
Fortunately, most people are in condition white and are unlikely to notice if your handgun prints.