The double jellies are contained in eight single-candy islands to the left and right of the main board. The jelly can only be removed with special candies (horizontal stripes, or candy combinations).
There are also vertical striped candies in marmalade in the top islands on each side of the board. Once set off, these can be used to destroy a layer of jelly on all of the islands on that side of the board.
There is a marmalade-coated colour bomb in the middle of the board that can be used to clear difficult-to-reach jellies.
There are two moon strucks, which makes it fairly easy to create special candies.
Create as many horizontal striped candies as possible; particularly near the top of the board in the hopes of releasing the marmalade-coated vertical-striped candies. Creating any combination with the colour bomb will generally clear more jelly than simply using it on its own.
However, if the marmalade-coated vertical striped candies are of the same colour, it may be nearly as helpful to simply use the colour bomb on that colour.