I usually set out a 50lb salt block and the Deer hit it year round I also do the same as AR Bowhunter and put out the rock salt too....it goes in the ground quicker and can't be stolen or packed off like a big Ol salt block!
Another thing we do is put out an Arm & Hammer Salt lick.You take a shovel and dig up the ground in a 3x3 or 4x4 circle busting up the dirt as fine as You can then take a box of Arm & Hammer Super Washing Soda and spread about 1/2 of it on the dirt,then spread about 20-30 lbs of Rock salt on top then pour the rest of the A&H on top and let the rain work it into the ground.Theres something in the A&H that enhances the salt and the Deer will hit it even more than plain salt.Some times I will also add some "Lucky Buck" mineral to the Lick to help with the Antler Growth on the Bucks!