The RPG is limited to the mark 1 eyeball for target detection, although I believe many models have some sort of simple optical sight. In a high RPG environment, soldiers should counteract enemy RPG gunners by stealth and evasion. Great small unit leaders (here are the strategic corporals, again) can ensure noise and light discipline. Platoon commanders and squad leaders need to avoid taking up obvious, commanding positions, because they will draw fire. Reduced use of armor, especially tanks, to limit the force's logistical footprint - which limits the number of supply/fuel trucks on the road to get hit. Use of smoke to cover movement, along with careful selection of the angles of attack, etc. Increased use of night attacks or bad weather.

On the defense, it's necessary to have aggressive patrolling and outposts. Camouflage is vital as well. The use of dummies and decoy targets might also be considered. An empty tent with a big fat red cross on it, for example, might draw a Hezbollah RPG team into wasting rockets at long range without first verifying their target, for example.

In any event, solid marksmanship and the ability to call down supporting artillery or tank fires in a quick, accurate fashion should be sufficient to kill off any RPG teams that get a shot off.

Really, all of this stuff is the same sort of tactical basics you'd take if your enemy had an advantage like air or fire superiority. It comes down to common sense, hard work and respect for what your enemy can do. The IDF has Hezbollah woefully out gunned, but they will take losses just the same if they get stupid, lazy or cocky.