General strategy for limited steps Portal levels

Solution 1:

1. Steps inside the elevator don't count. If you run and jump out of the elevator, it only uses 1 step (if you don't move forward when you land).
2. Falling from one portal into the other is very useful and uses no steps. With forward momentum and perfect portal shooting, you can chain a series of portals so that you jump into one on the floor, come out of the ceiling ahead, shoot and fall into one further ahead on the floor, shoot and fall out of one further ahead on the ceiling, etc. (YouTube example for #1 and #2)
3. As you mentioned, portal placement. A lot of the levels can be navigated around with only a couple steps if you're "thinking with portals".

Those are how I got all the gold achievements for steps in Portal, nothing more complicated.

Solution 2:

This goes along with Matthew's general tips, but I think it's key, as you can't use the portals for moving yourself all the time, but sometimes to move boxes/etc.

• If you aren't moving too fast (from too high) when you land vertically (e.g. after going up and down through portals on the floor), it will not count as a step if you remove a portal from under you. If you need to cut your altitude, throw a portal under a small overhang so you'll bang your head on that to spare your feet.