Read the ****ing manual, or RTFM for short.
I don't know if Dominantly was trolling or what, but you don't NEED that high of a shutter speed for a portrait, and you also don't NEED a monopod (although I'm not saying it would hurt).
The reason that you were told that shooting on 1/30s was incorrect is because your focal length is 58mm. The rule of thumb is that your shutter speed needs to be AT LEAST 1/focal length. So that means if 1/58s was an exposure stop, you would need to maintain a shutter speed faster than that. Meaning 1/80s should be your MINIMUM shutter speed (figuring in crop factor as well) when using that lens without a tripod or some form of extra stabilization.
That lens should be sharp enough from f/2.2 - f/3.2, giving you more leeway with your shutter speed, because your lens is letting more light in than at f/4.
If you still don't understand what I just covered in this post, read the ****ing manual again.
Good luck.