My leather restraints can keep me quite secure. Security depends on what you're connecting them to! If the "under the bed" system doesn't work for you, you might just get some rope and metal clips from the hardware store and rig something up on your bed, attached to the legs and running under the mattress, if you need to. You'll have to learn to tie some knots, and you'll probably want to set up most of the rope before you start the sexy time (unless the frustration of tying ropes to your bed adds to the fun!). My setup allows me to clip the restraints on when I want them and tuck them under the bed skirt when I don't want anyone to see them.

If you're interested in being tied up with rope, there are a ton of resources online. I don't use rope on my own skin, only to tie restraints and clips to other things, but the type of rope you use on your skin is very important for your own safety and comfort, so you should check out Twisted Monk for the good stuff.

I mostly agree, but if you do get rope from a hardware store, make sure it's soft and preferably cotton. We played with nylon rope. Once. Not pleasant.