Banana

The most important step is to get the base shape of the banana.

Create a rectangle and then segment the lines to subsections. In Inkscape - convert the rectangle using Path > Object to Path. After that, using the node edit tool [F2] select the four nodes and select all the nodes, and use the first tool button (on the top below menu), to insert new nodes between selected nodes. Do this three times.

After that, with the node edit tool still selected, move the nodes to get the basic shapes proper - use reference images if needed. After that, smooth out all the nodes except the three nodes each on both sides.

Base Colors

Create another inner shape using similar method, and make a copy of it and place it exactly over the same place. In Inkscape, use [Ctrl]+[C] and [Ctrl]+[Alt]+[V].

After that, prepare a color palette. This would make it easier to assign colors to shapes as you create them later on. (Copy the image to your local PC, and import it into Inkscape - then you can use the Eyedropper tool to select the colors I selected above). Give the outer shape the darker brownish tone, and one of the inner shapes the mid-tone (yellow) at 50% opacity. Over it, on the second of the shapes, give it the green color - again at 50% opacity, along wtih the gradient applied at the point where it meets the flesh of the banana.

Details

After this point, it is up to you in terms of the amount of details you can put into it.

Draw new shapes, and copies of the inner banana shape to create panel like parts of the banana peel. Use different opacity percentages for the mid tone color to create a sense of depth. Turn off the outline of all the shapes and you should get a good illustration of a banana.

I went ahead and added some blemishes and subtle texture details.