A colloidal suspension can show a variety of phases depending on temperature, effective volume fraction and nature of interparticle interactions. Dense aqueous suspensions of soft colloidal particles are often used as model systems to study glass transition dynamics. I shall start by introducing different types of colloidal systems and how one can experimentally characterize dense suspensions. After briefly discussing the experimental techniques used in this thesis to investigate the slowing down dynamics of soft colloidal suspensions near their jamming transitions, I shall describe our experiments performed to quantify the influence of solvent structures and inter-particle electrostatic interactions on the aging dynamics and rheology of aqueous suspensions of a colloidal smectite clay. Our study highlights that solvent structure is a key parameter in determining the dynamics and rheology of suspensions of smectite clay colloids. However, electrostatic interparticle interactions always dominate over changes in solvent structure when ionic additives are incorporated in the suspensions. I shall next show that aqueous suspensions of clay particles with different thermal histories can exhibit distinct aging dynamics. After discussing how thermoresponsive hydrogel particles of different sizes and stiffnesses can be synthesized by varying the concentrations of reaction ingredients during the synthesis process, I shall describe the various rheological properties and self- assembled morphologies of dense suspensions of PNIPAM hydrogel particles of different sizes and stiffnesses at different suspension temperature. We report that suspensions comprising the softest PNIPAM particles show a solid to solid transition with increase in suspension temperature while passing through an intermediate liquid-like state. The suspensions of stiff particles, in contrast, exhibit a solid to solid transition across the LCST with an intervening solid-like phase of low rigidity. I shall show how the rheo-dielectric technique, widely used to study soft materials such as liquid crystals, polymers, etc., can be a powerful method to study the dynamical behaviour of dense suspensions of soft glassy materials at different length scales. Our study reveals that while the polarization fluctuations of densely-packed PNIPAM suspensions slow down with increase in applied oscillatory strain amplitudes at a temperature below the LCST, the bulk stress relaxation dynamics speed up under identical conditions.  Finally, I shall discuss the synthesis of thermoresponsive core-shell particles with core and shell having different lower critical solution temperatures. The combination of distinct monomers that form the core and shell of each particle results in a hydrogel with extraordinary linear swelling and rheological properties. In our rheological experiments with dense aqueous suspensions of these particles, we observe three-step changes in the viscoelastic moduli with increase in suspension temperature. We perform large amplitude oscillatory shear (LAOS) experiments to study the non-linear rheology of the suspensions.