Harry Redknapp’s side made a bright start at Upton Park, with new £8m signing Loic Remy scoring inside eight minutes to put the visitors ahead.
However, Joe Cole restored parity in the second half and the Hoops came under intense pressure as the Hammers pushed for a late winner.
“We have realised now we have to be tight all over the park,” Hill told the Fulham Chronicle.
“We had been giving teams far too much time on the ball and we have tried to rectify that.
“It’s been a terrible season for us, but we’re trying to sort that out, and we’re starting to click both as a team and a unit at the back.
“We have found something extra these last four or five weeks and we are now much harder to beat.”