Si-nanoparticles (NP) are attracting steadily growing interest due to their intriguing sizedependent optical properties. The most challenging task in preparing Si-NP is to succeed in controlling the particle size and size distribution and the surface properties. To this respect, the method of laser synthesis of Si-NP from gas phase reactants appears as an ideal tool, being a very versatile and controllable synthesis technique, but the collected Si-NP are strongly agglomerated. Here we report on attempts to decrease the agglomeration of the Si NP by following two complementary strategies: - investigation and control of nanoparticle formation and growth during the synthesis process; - dispersion of the agglomerates and termination of the particle surfaces by controlled chemical etching followed by surface passivation and stabilization treatments. The properties of as-prepared and processed Si NP will be presented and discussed.