I personally use Whisper White cardboard from Stamping Up, but there are other brands that work just as well including one produced by Copic. Your cardboard needs to stand up to a fair amount of liquid without pilling or tearing. Don't underestimate how important it is to use a good base.
Identify the position of your highlights by deciding which direction the light source is coming from. I want my light to be in front and slightly above my pear, which means that the highlights will be almost at the top of the pear and leaves. Colour the pear with YG03, leaving the highlight areas blank as in the picture below. I prefer to have jagged edges where my colours finish as I find it blends easier, but that's a matter of preference.
Add a few little "imperfections" to the pear using E35. Once we blend over the top with the other shades of green, these won't appear quite so obvious, but they do add interest to the overall design.
Add a shadow with YG05 below the leaf that is covering the pear.
Add more shadows with YG05 to the bottom of the pear and around the "waist". Refer to the picture for placement. You can already see how the colours are starting to shape and round out the fruit.
Deepen the shadows with YG07, keeping the colour to the very edges of the pear in a narrow strip. Don't take this darkest colour into the lightest green, you should be able to see three distinct shades at this stage.
Starting in the darkest green area, blend your colours together using the YG03 marker in small circles. Work around the pear, slowly making your way to the blank highlight areas, filling them in last to keep those areas of the fruit lightest.
Use the 0 blending pen in small circles over the highlight areas to strengthen the highlight and add further dimension to your pear.
Use E25 to colour the branch and down into the spine of the leaves. Don't bring the colour all the way to the end, but don't stop it abruptly either. It will look better if you have a little of the brown mixed with the green. Refer to the picture below.
Add shadows to the branch with E27. Make sure you darken areas that are behind other things or in crevices. Use E27 to colour the core at the bottom of the pear.
Add the darkest shadows to the branch and core of the pear with E29. I generally don't blend branches or tree trunks as I like the rougher look, but you can if you prefer by using the E25 marker to blend the three different browns together.
Colour the leaves, including the stems, with G12 leaving the highlight areas blank on the top two leaves. We want the back leaf to be slightly darker to give the impression of depth. Darker colours recede while lighter ones come forward.