Wash the berries and drain in a colander. I typically don't wash delicate berries like raspberries and blackberries, just remove any stems and leaves. Pour the washed berries onto a clean tea towel to help dry them and go through the berries and pull out any that are squished or bruised and pull off any leaves/stalks.
Once the berries are dry, transfer them onto a the rimmed baking sheet/tray that is lined with baking paper or a silicone liner. Place the tray directly in the freezer (I don't bother covering it)
Once the berries are frozen (I leave them overnight) remove the tray from the freezer and transfer the frozen berries into snaplock bags, containers or jars.