Best thing to do, if you're 18+(I think), is to head to Redridge Mountains and head, I believe, North along the road out of Lakeshire. Follow it for a while and then there'll be a fork going North and another pass leading East. Head east and at the bottom of that small hill is a Mill with several locked boxes inside it. Now, when you open these boxes, you'll get turned into a rat or frostnova'd in place. Do not worry, you can still pick the locks I believe and they don't last that long.
You can position yourself between two of the boxes and alternate between the two for quicker picking. This should take you easily into the 60's or 70's in skill. Now, remember that lockpicking is dependent on your level. Your max skill will be 5 x Current level. So, if you're too low, go and level and come back until they turn green or grey to you.
Just be careful there, there are wandering spiders and vulture mobs nearby that may spot and aggro you in there. but if you're level 18+ you should be able to handle them one at a time^^. It would help to bring some Anti-venom if you're first aid skill is high enough.
Good luck^^