In a recent paper \cite{Zhang-Xiao}, Zhang and Xiao describe a technique on constructing almost optimal resilient functions on even number of variables. In this paper, we will present an extensive study of the constructions of almost optimal resilient functions by using the generalized Maiorana-McFarland (GMM) construction technique. It is shown that for any given $m$, it is possible to construct infinitely many $n$-variable ($n$ even), $m$-resilient Boolean functions with nonlinearity equal to $2^{n-1}-2^{n/2-1}-2^{k-1}$ where $k<n/2$. A generalized version of GMM construction is further described to obtain almost optimal resilient functions with higher nonlinearity. We then modify the GMM construction slightly to make the constructed functions satisfying strict avalanche criterion (SAC). Furthermore we can obtain infinitely many new resilient functions with nonlinearity $>2^{n-2}-2^{(n-1)/2}$ ($n$ odd) by using Patterson-Wiedemann functions or Kavut-Y$\ddot{u}$cel functions. Finally, we provide a GMM construction technique for multiple-output almost optimal $m$-resilient functions $F: \mathbb{F}_2^n\mapsto \mathbb{F}_2^r$ ($n$ even) with nonlinearity $>2^{n-1}-2^{n/2}$. Using the methods proposed in this paper, a large class of previously unknown cryptographic resilient functions are obtained.