I would say SL42 is actually quite low for a first attempt at O and S. Do-able, but definitely anything up to 60-70 is a good level without being massively OP. So, don't be too frustrated by your lack of success, that is a fairly low level to take them on
You'll get it though, what kind of build are you? If you have a decently levelled pyro glove with some high level spells like great fireball/great combustion they can take out O and S fairly sharpish.
Also, going backwards from Anor can be a bad thing. If you want to grind and level a bit, just use the bonfire that's just after the two archers where Solaire sits. From there, you can kill four silver knights and then just return to bonfire and repeat. If you get good at parrying them and use a weapon that OHKO's them, you'll get 5,000 odd souls a run. If you want to increase the chances of big money, big prizes; then stick a summon sign of your own down whilst doing this. Can end up getting a nice healthy 50,000 souls for helping someone else kill O and S, not to mention the practice at killing them.
Other than that, I'm a bit of an O and S expert, and I think I have a SL50 character on PS3 knocking about somewhere that could stick a sign down for you. Probably even has a spare weapon or two floating about that you could have
Edited by puddleduck at 23:45:34 21-02-2013