well, root and nuke is about all you can do solo. At 29 you get Bonds of Force an aoe snare and an aoe damge spell (I forget the name), this is where you start quadding and the xp flows.
But back to 13... If you need plat I suggest killing wisps in WC or EC theres also a Island near Erudin full of wisps. Collect the Greater lightstones and save em,s sell the plain lightstones to a merchant. GLS's are for a quest and the reward is a book for each greater lightstone you turn in. The turn in npc's, for good races, are in NK at the gypsy camp, Oasis at the gypsy camp. Evil races can turn in the GLS's in S Ro at the DE camp in the desert. I am not sure of the names but if you give it to the wrong one she'll give it back.
GIVE don't sell the GLS to the gypsy and she gives you a book. The book can only go in a main slot so give only as many GLS's as you have empty slots or the books fall on the ground. Then sell the books back to the gypsy, for 9 pp ( I go to another gypsy in the same camp as I seem to get a p or two more ). IF you sell the GLS to merchants you only get 3 pp. This kept me in plat for sow and temp until I was high enough to do giants.
As far as XP - root and nuke solo or get into a good group in PC ( tough on my server as PC is always full ) around level 16 -17 or so . For those who don't know don't wander around PC but stay at the entrance shouting for groups and watch for trains in there and zone if you see a train call.
If your still around 13 , 14 try getting a group in orc camps - either in CB or in EC. CB has nasty trains also.
If you group wait until the tank has the mob to 75% before casting so you don't draw aggro and pull the mob from the tank. Once hes at 75% then DD him and wait for a few seconds ( don't chain cast ) before hitting him again. IF your not casting in a group you should be sitting and medding to recover mana.
hope this helps some.