The problem with neglecting lockpicking is that you have to go back to lesser mobs to PP the junkboxes needed for your LP level.
It's too late for the OP, but first advice is don't neglect it. Every level or two, make a concious effort to PP until you get enough boxes to max your LP skill.
Also keep an eye out for locked doors/chests.
Scarlet Monastery has two doors that will give skill-ups for quite a stretch, although you need patience for their resets.
Blackrock Depths has 3 doors that will give skillups without encountering a single enemy, and a 4th if you have sufficient stealth. They also reset on instance reset. That means you can gain 15-20 skillup points in less than an hour, before having to wait for the instance reset CD. I got skillups on these doors all the way to 300.
The service entrance of Stratholme has a gate that is orange even at lvl 300 LP
Ramparts has a chest early in the instance that is still red at 280 LP