None of this is with solo play in mind because the slayer is such a group dependant mdps, in my play time (NA and oceanic) I have not seen any played well out of group.
Accessories: The slayer is AP dependant even with WP and RP, your choice jewls and back piece should attempt to counter this. Look for +str and +AP jewls/cape on the AH. If you can't find them, the +30 Str and +20 wounds cape and +20 str +x weaponskill or +20 str/wounds jewls are options. Because of the high burst damage from sorcs, the accessories you select should idealy have a considerable +spirit resistance on them as well for help with mitigating sorcs.
The slayer, with fast weapon speed, high strength and high crit values also benefits from AA speed increases. The tactic push for more and the tome jewls Oath stones
viewtopic.php?f=8&t=13566&hilit=Oathstones can be useful.
Renown: once you have your gear and potions, then consider what classes you will be running with and what buffs they provide. For example, a knight can provide Str and crit bonuses, a IB can buff your weapon skill and debuff armor, a WL can debuff armor and a SM can randomly stat steal. Add these potential bonuses to your stats based on the output from .getstats and then look to further adjust with your renown.