The complex and far-from-intuitive issue of establishing how and when to ac
t when manoeuvres are to be performed in space is discussed here in a simpl
e graphical way. An analysis was made of the effects on the parameters of a
n orbit of low thrusts in three directions: tangential to the orbit; normal
to it in the orbit plane; and normal to the orbit plane. An outcome is tha
t, in order to obtain a desired effect, and at the same time minimize the u
ndesired ones, it is better to use only a tangential thrust or only a norma
l one rather than a combination of simultaneous tangential and normal thrus
ts. Thus it is not necessary to investigate any alternative orientation of
the thrusters. A manoeuvre can be accomplished by thrusts given either only
once along the orbit path, or in more than one orbital point. Diagrams are
produced which give a quick insight into the manoeuvre philosophy for both
kinds of action.