Scenarios based on Internal Transport Barriers (ITBs) are highly desirable for a steady state tokamak reactor, because together with good confinement characteristics, strong pressure gradients are built inside. These originate a high bootstrap current, which in turn reduces the demand on the external current drive (CD) source needed to operate without the ohmic transformer. Then, a large effort is being spent in the tokamak community to identify an ITB regime, suitable for ITER, whose properties are preserved for several diffusion times of the plasma current. Indeed, at present, an ITB regime is often terminated by MHD (Magneto-Hydro-Dynamic) instabilities linked to the pressure gradients and to the safety factor q. On the other hand, q itself and the associated magnetic shear (s=r/q·dq/dr) play also an important role in the triggering and in the performances of ITBs. The working point in this many parameter space must then be chosen carefully and several quantities need to be controlled in order to attain stationarity. The present paper describes the experiments carried out at JET to establish a long lasting ITB by a proper choice of parameters. The final goal is to achieve full control in real time of the ITB strength and radial extension and of the q profile by means of the external power sources.