Depends on the weed. Basic garden weeds I pull by hand, and weeds around path edges have boiling water poured on them! If you have a steamer they work even better.
Insidious nasties still get the roundup!
I do it purely in the good, ol' fashioned (and sometimes back-ache inducing) way of taking them out by hand after giving the soil a good soaking to ease the roots out more efficiently. I would certainly advice everyone NOT to utilize weedicides, they only end up in waterways and do much more damage than good.
I try and pull out weeds when I can. If they're in difficult to reach places, I'll just keep pulling on the leaves until they're just sick and tired of getting harassed all of the time. As long as I get them before they flower, then I'm happy!
It depends on the weed and where it is. I also pour boiling water on weeds in paths and other hard paved areas but my brother once poured a kettleful on a dandelion in the middle of his lawn and managed to kill off more grass than weed..... idiot!
Dandelions in the lawn here get salt sprinkled directly into the middle, if they are in flower beds then they are dug up though their roots are so long it takes several goes to finally kill them off.
Most other weeds I just pull up as and when I spot them. I don't use any kind of chemical weedkiller as I have a cat and a small boy and worry about them ingesting it.
I don't use poisons for the same reasons. We animals that frequent most of the garden and it would just be terrible if they were affected by a spray. And the fact that we collect eggs from them means we would also worry about our own health.