I was pretty unsucessful yesterday
Just to clarify things, was that because you weren't getting many chances, or because you were missing them?
In the first case, as ever with pigeon shooting, keeping an eye on the pigeons' movements and the wind conditions is vital. In light winds and with clear skies they'll often circle high like duck and then drop straight into the trees, giving you little choice other than to shoot them out of the branches. But when the wind is stiffer and the clouds are low the pigeons will tend to come in lower too, keeping in the lee of the wood before flaring up over the treetops and dropping into their chosen roosting spot.
In the first sort of weather an air rifle would be my tool of choice, but there's nothing like a shotgun for the blustery evenings. Personally, I find lofted decoys more help when airgun hunting, since they can bring the birds right in close, but when out with the shotgun I see positioning as more important. You don't always need to be in the roosting wood itself, either, as often a spot on a downwind hedgerow gives better visibility and fields of fire.
There's a roost in a narrow wooded valley near me, where when the wind is right the pigeons stream in low over a pasture with a long ridge in the middle. If you stand with your back to the wood and watch the ridgeline it can be like your own private grouse drive! On occasion I've even lined out half a dozen guns along there and we've all had plenty of shooting.
But it only works if the weather's right. Each wood will have a set of conditions that makes it the one to go for on a given evening, and part of getting to know your ground is figuring out what these are. You won't get it right every time, but at least you'll know which way to bet. Just make sure when it starts to come together that you don't over-shoot any one spot - make the pigeons do the guessing for a change!