Obviously moving the weight the furthest in the direction needed will be the most effective. With that being said, it's often necessary to make and mold your own ballast.

Take some scrap balsa, and build a "cast." Be it in the shape of a square, rectangle, triangle...whatever you need. Make sure that it is water-tight, because you're going to pour molten lead into it.

Hit up your tackle box, or head to the bait shop for some split shot, or heavy sinkers, or whatevers most available and economical. Go into your pantry and eat a small can of corn, or beans...just make sure it comes out of a tin can..or whatever metal it is. The metal in this can will withstand the same heat that will cause lead to melt.

Clean the can. Squeeze/deform the can as to make a little "spout," resembling something that you see on a juice pitcher.

GO OUTSIDE.

Put your balsa mold on the ground, put the lead in the can, and take a blow torch and heat the lead until it becomes molten (This doesn't take very long)

Once it's all liquid, put the torch to the side, and using a channel locks, or something to hold the can, pour the lead into the mold.

ONCE AGAIN...Go outside for this! Obviously be careful with the torch and the molten lead.....but be more careful not to breathe any fumes, and wash your hands when your done. Always wash your hands when your finished handling lead.