Good radar usage starts with the weather channel briefing and a look at the radar summary. Decide before you takeoff what you're up against. Tops over FL300 get my attention real fast. Are they isolated or are they part of "train" of TS? Which way is the train moving? Central US and parts eastward are prone to "freight train types of TS" one after the other all afternoon long. Best strategy, if you're just wasting gas waiting for the train to pass, is to land and go have a cup of coffee.
Look for shadows, they're the real killers. Not all RED cells are created equal. To see shadows you must have your're radar looking down. The shadow reveals themselves as a "black cone shaped spoke". Some radars have PAC alerts, look for these. Decide if these killer cells pose a problem for the terminal area. If it paints a shadow at 80 miles it's a killer.
The best evaluation altitude is 10000 feet 40 miles from the field. This is your final chance to work a plan. Scan up and down. I enter terminal areas with 7 degrees up in the Cal setting. If the gain can be reduced and I'm experiencing REDOUT, I'll reduce the gain one or two clicks.
Listen up for wind reports on the field. Listen for indications of "first gusts". If you hear calm wind reports and then sudden increases in wind speeds or heavy rain while you're being vectored around, take the cowards way out and ask for a vector to your alternate.
Some approach controllers have excellent radars that can differentiate Level V and below. They have the big picture. I've found that, in the US at least, what I see on radar is very near what approach control sees on his radar. This is true, at least as far as killers TS are concerned. He can't see the speed bumps or rough rides but he can see a storm that will shake the pods of the plane. He can also tell if they'll need to be closing the field soon or better ways to approach the field. Listen to his advice.
Anyways remember we get paid by minute. It's your license. And when you end up off the end of the runway in heavy rain with the slides deployed with angry wet and injured passengers...... at your hearing they (FAA) will simply ask you....."Why didn't you just divert to your alternate, have a cup of coffee and watch the storm on the radar summary in base ops". Yeah?! Why didn't I just divert to my alternate. Have that ringing in your ears for the next 5-10 years!
Last time I remember slugging it out with dangerous storms closing on the field, I don't recall getting an "Atta Boy" from the company. They can Kiss MY @$$!