Chocolate drizzle decoration are simple to make and you can easily achieve great results.

Start by melting some chocolate in the
microwave or bain marie & put in a piping bag made from
greaseproof paper or a fine tip squeeze it bottle.
Don't use a metal
icing tip in your bag or the chocolate will set on contact and they are
not easy to clean!
Snip the end from your greaseproof paper bag to
create a fine hole and on baking parchment/greaseproof paper drizzle
the chocolate into whatever shape you want.
Allow to set or place in the fridge to speed things up.