Clustering in Mobile Ad Hoc Networks (MANETs) has many advantages compared to the traditional networks. But the highly dynamic and unstable nature of MANETs makes it difficult for the cluster based routing protocols to divide a mobile network into clusters and determination of cluster heads for each cluster. In this paper, we analyze and compare some of existing works on clustering in MANETs. We categorize the works as Location based, Neighbor based, Power Based, Artificial Intelligence Based, Mobility based and Weight Based. We also present the advantages and disadvantages of these techniques and suggest a best clustering approach based on the observation.