How did you start your GaEE? I've tried it a few times, but had trouble getting to the Lair.
Honestly, it took me three tries before getting past D:4, although I was being reckless at first, to test what I could or could not do.
Basically, the hard part is surviving until you can cast stone arrow three times in a row. Train earth magic, and also a bit of conjuration, until you can cast it reliably, then train spellcasting until you reach 9MP. Or the other way around, I am not sure: normal sandblast doesn't depend much on your spellpower, but sandblast with stone does.
Sandblast is a very powerful spell, but suffers from the fact that its range is atrocious, and that it counts AC three times (although this shouldn't pose much of a problem at first). You do start with 20 stones, so you can throw one at an enemy on the edge of your LoS, and back-off to known terrain, where you can pelt it until it reaches sandblast range. Replace stones with darts as soon as get them, darts are amazing in the early game even at 0 throwing.
And in a pinch, you can wield stones to boost sandblast with one extra range and ridiculous damage levels (anywhere from +50% to +200% depending on spellpower), even higher than stone arrow! It consumes a stone and the time it takes to wield a stone, but you can tackle dangerous enemies earlier than normal.
I've been using stone arrow as one of my main damage sources all the way into Snake Pit 5, even though by then I should have changed to stronger spells, so you should be fine once you reach level 3 and 9MP.
I have no idea how you are supposed to use LRD effectively, though. It's waaaaaay too noisy, enemies must be standing right next to a wall, and also counts AC three times, so if there's any band of roving orcs around, good luck. It is LOS smite-targeted though.
I am also irrationally afraid of single-target all-or-nothing spells, so I don't use petrify.
That's how I did it, which doesn't necessarily mean it is the best/safest way. Luck is also involved.