taking cuttings from a woody shrub

how would I go about it? Is there any rooting stuff I need to buy? Or is it clip plant in compost and go? I really am a beginner, but there's a shrub in a very overgrown part of my garden I'd like to keep ideally - the parent plant is far to big and straggly / caught up in brambles to keep

 

It all depends on what shrub you have.

Many will take if you look for the new growth, snip some tips so that you have pieces 5 or 6 inches long, remove the bottom leaves keeping at least 4 and then put them into pots of moist compost. Put something longer into the pot so that you can cover with a polythene bag and seal to maintain the moisture. Roots should develop in a few weeks, the sign will be that the plant is alive and eventually grows.

However, it is much better if you can identify the plant and get the specific instructions for that particular one.