The Eifel Tower is easily walk-able from most places in the center of the city.
The easiest way to get there is probably the Metro system. Just take the metro to Champ de Mars, Trocadéro or Ecole Militaire and from any of these you should be able to easily see the tower.
Best view of the tower is probably from Trocadéro but it is also the furthest away. about 7 years ago