Four and five year olds are such "doers". They have to touch it, manipulate it, try it, and often taste it! I have frequently sprawled on the floor with a few kids to "play" with quisinere (sp?) rods to build things. As I am building I verbalize decisions that I am making to solve problems. "This 4 is not long enough to reach the other side...I may need a five or six to make it work. What do you think Mike?" As I model this problem solving strategy, it is literally moments until I hear kids starting to use the same kind of thinking out loud.
I also use brainstorming alot! I keep tear sheets handy, so that any time we run across a dilema, we can brainstorm ideas. I use simple illustrations along with words to help them "read" the possible solutions.