It enters most easily via your airway, via inhalation or one of the hundreds of times a day you touch your nose, mouth, eyes etc. Basically the same way you get a cold.
Wearing a mask, properly, washing your hands often and well, and never touching your face may improve your chances.
A Chinese study suggests that 2019 nCoV binds to the ACE2 receptor, common for these bat coronaviruses, apparently. Heart, lungs, kidneys. Already suppressed ACE2 in diabetics, so you begin to get a feel for where lots of the complications are cropping up: COPD sufferers, those with heart disease and diabetics, to name only three groups.