Removing a subject from the background

[SAEngraver]

Hail the reader,
When following the steps as per procedure taken from a video tut the active stipple line which is supposed to select the area one wishes to retain when inverted - does not stay within the subject I select, it randomly includes large areas of the pic I do not want to retain... her is my method -... what am I doing wrong please?

1. bring pic into editing screen
2. right click on palette image and select - "promote background layer"on from top on left of screen - the "smart selection tool"
3. Set mode to add
4.Click and drag brush over areas wishing to be retained (this is where it goes wrong - it selects large areas outside my retention area- have used a multitude of pics in this trial - thinking it was the choice of pic, but same result.
From here it should proceed as follows
a. in Selection pull down menu select invert should now be without background.
As said, I can not get to point "a" as it continues to select large unwanted areas.
I thank the potential kind soul for his/her help in advance--- have tried for a few days and studied on the subject what I could find - but my frustration has gotten the better of me - I need redemption please.
Thank you
b. hit delete key and the image shoul n
3. select - in third ic
3.

[LeviFiction]

Is feathering set to 0?