To the reverse slope,flank shots, low tech numbers vs high tech=hich cost approach add:
1. the obvious: don't target units you have little chance of disrupting/damaging/killing, ie forget the Markavas go for the APCs etc (if there are not around yet,wait...)
2. try to "separate" the attacking armour from its accompanying mechanized element. Arty and arty delivered mines may help at this. A forward "skirmish" line may also do the trick. If some of your forward units survive the armor onslaught, they might cause the mechanized element to unload. Then apply artillery as usual. The armour element may continue to advance but without infantry support.Your chances are better now (well in the theory!
)
Avoid the strong(er), hit the weak(er).