I was advised to cut my lilac flowers off after they had flowered, idid as much as I could reach
now I have flowers at the top where I could not reach and my neighbour who did not prune her side has loads of blooms. Was I given wrong advise.
Not it's not necessary to dead head lilac. Paddywak's link will tell you how to prune though. I do nothing to my lilac and it stands in a huge garden so can grow huge and this year is is absolutely full of flowers.