Can anyone give me some good references to read geometric K-homology. I know bit of Kasparov's KK theory and analytic K-homology.
If I remenber correctly one can use, Martin Jakob's geometric approach to generalized homology theories:
Jakob, Martin An alternative approach to homology. Une dégustation topologique [Topological morsels]: homotopy theory in the Swiss Alps (Arolla, 1999), 87–97, Contemp. Math., 265, Amer. Math. Soc., Providence, RI, 2000.
Jakob, Martin A bordism-type description of homology. Manuscripta Math. 96 (1998), no. 1, 67–80.
Baum-Douglas geometric K-homology groups are defined in this way, this is very well explained in (sections 4 and 5 in the arXiv version):
Baum, Paul; Higson, Nigel; Schick, Thomas On the equivalence of geometric and analytic $K$-homology. Pure Appl. Math. Q. 3 (2007), no. 1, part 3, 1–24.