Less than 1 month –
10-30 hrs/week –
Long tail keyword generation plus Google Adwords Keyword Planner
analysis of created long tails to extract those with actual searches.
Here is how I do it manually.
I create a list of long tail components like
and I combine them with geographic or other modifiers like
new york city
and often insert words like "in" or "located in" or "in downtown", in addition, between the sets.
This creates the following long tail ...