Welcome!
First off read this sticky as much as you can it'll help you out a ton :
http://forums.d2jsp.org/index.php?showtopic=23010118&f=272Second you find good items on LS just by playing it. Either by slashing and slashing killing monsters, or you can do a challenge monster "the well", or you can transmute items together. More items drop in catacombs than they do in arena now. And good items for a guardian are "Heal Mastery items", a good heal charm, and Intelligence items [you can either get intelligence or heal mastery] check out this guardian guide :
http://forums.d2jsp.org/index.php?showtopic=19782009&f=272