When you come to light your fire you’ll often find that the denser cold air trapped in the flue forces the smoke back down the chimney.
To combat this pop a firelighter on top of your wood. This will put your flame’s heat directly up the chimney with little smoke. This should give your chimney the heat it needs to clear the blockage of cold air ready for you to then light your fire.
Clean your Chimney
Open the Door Slowly
Burn Drier Wood
Improve the chimney's draw
A rotating aspirator cowl will assist the draw of the chimneys when it is windy. The rotating cowl will help move the cold air up and out of the chimney. This helps to keep air moving through the house in the correct direction.
Alternatively try a draft-booster fan. Built into a cowl, a draft-booster will suck air up the chimney creating positive pressure and boost the chimneys draught. It is worth noting that this solution will require an electric supply as well as regular maintenance to prevent a build-up of ash deposits. A build-up can cause it to stop working. However it will greatly aid in removing the cold air trapped inside your flue or chimney. Fans can be particulary useful when your flue/chimney is shorter than recommended.