The two best tools are an in-line meter and a tach.

Plug the meter between the battery and ESC and do some runs with different props. The meter tells you the current draw and the tack tells you the rpm.

My most recent test was picking out a prop for a glider. The OEM motor had eaten itself up and the replacement didn't show up in any of the available applications.

I knew the advertised power for the motor in watts. That was what I wanted to see on the meter with at least one of my props. I ran every prop I had and wrote each ones numbers down as I went. The one that was closest to being right on was what I flew first. Then flew a couple that were close. Got a couple of prop choices out of the test and didn't waste time flying every one in the pile.

Climb was the only parameter that mattered for my glider. The rpm really isn't important for that. But it matters for other model types so I've gotten used to recording it no matter what. I did a prop test awhile back on a buddy's daily flyer and picked the 1st to fly from the meter reading and the rpm. The rpm isn't actually of much concern unless you're worried about either the top speed or the landing speed. You're going to test fly after all.

The ground tests just save you time by rejecting some of the available. Truth is, I don't rely much on the online applications except to suggest what props to take out to the test.

Watts Up meter. Best purchase for electrics since I got into the silent side. http://www3.towerhobbies.com/cgi-bin...&I=LXLMV0&P=ML