coordination

Read this mate...
http://targetiit.com/iit-jee-forum/posts/hybridization-and-geometry-simplified-2283.html

Also tis one is good...
http://targetiit.com/iit-jee-forum/posts/coordination-compounds-1767.html

the actual reason why dsp² is square planar while sp³ is tetrahedral.. lies in the orientation of orbitals..in dsp² the orbitals under hybridisation are s, d_x²-y² , p_x and p_y they all lie in the x-y plane ..so it is square planar..
while in sp³ the orbitals under hybridisation are s, p_x, p_y and p_z...they all lie in different planes.. so it is tetrahedral..