Portal/Tips and advanced techniques

Basic tips

Not all steps implied as being necessary are actually necessary. Many pieces of levels can really be skipped.
Save your game after anything tricky or long, especially in the advanced chambers and challenges. The game automatically reloads when you die, but not if you don’t die, and not necessarily where you want it to.
Cameras are seemingly useless, but can really be very helpful. You can jump on them, hit pellets with them, or even knock out turrets.
Turn portal funnel on in the options, and look down when falling into floor portals. It is much easier to sail through this way.

Make your portals as accessible as possible. You may be able to use them again later.
Fling. Use that momentum. It’s fun, and gets you places you couldn’t normally get to.
Experiment! Explore every possibility. If you can find a tiny corner of a surface to get a portal on, try it. If you can shoot a portal while falling where you can’t on solid ground, try it.
You are allowed to get shot. Just don’t die.

Place one of your first portals right in front of the elevator. A step and a hop can get you there in 2 steps. A trickier technique (see below) can get you there in only 1.
Don’t step on objects like cubes (unless absolutely necessary); you’ll rack up steps for no reason.
Use lots of portals!
If you travel straight up through a floor portal, and then shoot that color portal elsewhere, you might not gain a step for landing if you are only traveling a small distance upwards. Floor portals are the most useful way to get around without stepping.
Alternating stepping and hopping, if done with the right timing, gets you farther per step on average than normal walking.
Play around with angles. Momentum applied at an angle into a portal can get you a lot further and help you take fewer steps when steps seem necessary. This will take a lot of experimentation to get the correct angles, but can be really impressive when you get it.

Portals are the fastest way to travel. If you need to take more than a few steps to get somewhere, portals may be faster.
Use alternate methods. If you discover another method while trying to do a different challenge, consider using it here, even if it uses more portals or steps than your best method.
Practice, practice, practice. Get your hands used to exactly how far you need to move.