I recommend not plucking, waxing or whatnot if you want them to grow in. Invest in either some castor oil or Ardell Brow and Lash Growth Accelerator. For a brow pencil, I prefer Almay Brow Defining Pencil. Powders = Ardell Brow Powder, NYC Browser Set or BeneFit Brow Zings. For brow "gel," MAC Brow Set or clear mascara.
If you're looking to grow them back into a particular shape, check into Ardell brow stencils. Find some similiar to the shape you want, and try to let your brows grow in "according to the stencil." I did that and went from literally pencil marking thin rounded brows to thicker, nicely arched (slight arch) brows... Almost Linda Evangelista like brows you could say. I've posted pics in another thread.