According to Cusick, Terry Nation, the Doctor Who writer who created the Daleks, suggested they should make a gliding movement "like the Georgian state dancers", but there was little other visual description in the script.
Cusick demonstrated the creature's style of movement by grabbing a pepperpot and sliding it across the table to the model maker Bill Roberts (whose company Shawcraft built the Daleks). An initial design involved the Dalek operator propelling the machine with a tricycle housed inside it but eventually the actors moved the squat, castor-mounted props along by shuffling their feet.
Raymond Cusick's involvement with the second Doctor Who adventure, The Daleks, in 1963, came by chance. The original designer was due to be Ridley Scott, but his schedule ended up clashing with the proposed filming dates.
Originally the Dalek creature remained a mystery. In the first Dalek story all that was shown was a claw hand sliding out from under a blanket. Later in the 60’s the Dalek appeared as a mutated ‘blob’. In the 80’s the same idea was applied, a green coloured mutation. Between 1963 and 1988 it was rare seeing the Dalek interior. A Dalek mutation was clearly shown (living and speaking) in the 2005 episode ‘Dalek’.
http://quotesgram.com/img/hedda-sterne-quotes/11757321/
http://www.jezzwarren.com/styled-14/blog-13/files/tag-props.html
http://www.thedoctorwhosite.co.uk/dalek/inside/