Immigrants and Brickwalls

I have read so many books on starting genealogy and researching your own family tree.    I have went several generations back on each line however, I am nowhere close to discovering an ancestor that came by boat from another country to this country.   I am excited to find one though, because it will be interesting to find  where they come from and why they came to this country.
I do have a couple of brick walls.   I sometimes think that I am not exhausting the search to see what else I could possibly find on each ancestor.   I think some of my "brick walls" would not be brick walls, if I would just take the time to research in greater depths.
Here are some of my problems...
On the Lemons side of the family - my line goes from Theodore to Samuel to William (1799) to his father who was also William.  After that William can find his father.   Its a theory that the surname Lemons, might have undergone a change in spelling to get to Lemons, maybe from Lyming or Lemmons.   I'm not sure to how to go back any further which is another
reason why I decided to take the DNA test.
Another problem.   My maternal grandfather is Frank Edward Maddle (1930-2004).  His mother Dora L Mccloud was not married when she got pregnant with my grandfather.   All we know is that his last name was Whittaker he died in the 1960's in possibly the White, Sparta, or Putnam county areas.   His mother then married Noah Madewell and that is how my grandfather got his last name.  This again was another reason why I decided to take the DNA test.

I need to start organizing my information better and start utilizing the forms that people have provided for free on the internet.   I am going to reread some of my books on genealogy and see where I might be messing up and not doing something right in researching.   I need to start making use of things specifically like research plans and calanders.   I have always loved organizing paperwork and using forms.  I just need to apply that to my family history research.