First, here is the graph, simply applying the graphing code for the site:
Factorize numerator and denominator completely, at least for Real number purposes.
No hole since no factor is common between numerator and denominator.
Undefined for x=1 and x=-2, so this causes vertical asymptotes.
Degree of numerator and denominator both EVEN and EQUAL, so as x tends unbounded in either direction, f approaches 1. Horizontal asymptote y=1.
Try polynomial long division. You will find 1 plus some rational expression, consistant with what is found as the horizontal asymptote. NO oblique asymptote!