1.  Define the Dimensions

Step 1

The tree should be taller than the character, but it should be shorter than a floor height, in case you want to make it part of an indoor scene. 

Step 2

Let's add a height marker for the trunk.  Because of the shape of the tree we'll never actually see the trunk, but we'll still use the references of these heights. 

Step 3

This is the angle I'll be using for my tree; it's a 3:1 diagonal line. 

Step 4

Copy it and flip it, and we get a triangle. 

Step 5

To turn the triangle into a cone shape, we'll need the bottom to be a circle.  The width of this circle should match the bottom triangle line, and the height should be half of the width. 

Create the circle in a New Layer.  You can do it with the Elliptical Marquee Tool, and while you're making it, check on the info panel to see your width in pixels.  Divide that by two and make the height that size.  The middle of this circle matches the triangle's bottom line. 

After you've done it, fill it with some color. 

Step 6

I softened some of the pixels on my circle as I thought they made the edge a bit more jagged than they should be.  Make a copy of this circle, place it in a New Layer and fill it with black.  This will be the shadow, which we'll apply in a while. 

Step 7

We'll take the solid circle shape and turn it into an outline.  It's easy to do by selecting the circle with the Magic Wand Tool, and then contracting the selection by 1 px (Select > Modify > Contract…). 

On the original triangle layer you'll want to remove the two bottom lines… but don't get rid of them yet, just set them aside. 

Step 8

You can now remove the back half of the circle, give it the same color as the triangle outline (black or nearly black), and Merge the two layers together. 

The bottom looks a little odd, so I adjusted the height on that portion. 

Step 9

Let's now retrieve our circular shadow and the trunk height markers.  Move the shadow's layer below the tree and give the layer 15% or 20% opacity. 

Then use the height markers to correctly place the shadow under the base of the cone. 

Step 10

Fill the cone with a nice shade of green and we're on our way. 

2.  Add Shading and Texture

We've got a basic cone shape down.  Let's bring it closer to looking like a tree. 

Step 1

This is unusual, but we'll deliberately make our shape more jagged.  Turn the diagonals into mostly vertical lines alternating with a single pixel, like so:

Step 2

A similar jaggedness can be applied to the bottom also.  This should help the cone look less perfect and a bit more organic. 

Step 3

As usual we'll shade the right side darker than the left side.  All the shading on the cone should have wedge shapes with the lines converging at the tip.  The diagonal on this line is 4:1 (that is 4 px going up for every 1 px going across.) 

Step 4

We can pretty much mirror that last shape for the lightest shade.  You might want the lighter shade to reach to the very top. 

Squeeze a wedge of the base color in between the dark and light shades to soften the transition. 

Step 5

We'll add one last color to the tree, which will be the darkest shade on the rightmost edge. 

Step 6

The shading can get the same jaggedness that the cone shape got.  Here it is applied on the darker shades...

… here on the lighter shades:

… and here also through the middle:

Step 7

We'll add one last small light effect here: making the darkest shade be 1 px away from the outline of the tree. 

Step 8

Now let's add just a little bit of texture.  We can base the texture on something like this:

It looks a little bit like leaves, but also a bit "pixely", which suits us.  It also matches the other trees I've covered in previous lessons, so it's good for consistency. 

Step 9

This texture changes the shading vertically, so if we applied it to the whole tree it would mess too much with our cone shading—it would look too complex and also would be hard to do!  So we'll only apply it to the bottom. 

Start by placing it on a New Layer, sticking to the bottom of the cone and adjusting to its curve. 

Step 10

And to apply the texture, go to the tree layer and with the Magic Wand Tool (set to 0 Tolerance and contiguous off) select all four shades of green of the tree.  Invert the selection (Select > Inverse) and on the texture layer hit Delete. 

Then lower the opacity of that layer to 50% or so, and Merge the texture layer with the tree layer (Command-E or Control-E merges down). 

And finally replace the darker shades of green you get with the four already chosen shades of green from before; I don't usually work with palette restrictions, but it's cleaner to avoid adding shades upon shades haphazardly. 

Step 11

We'll just do a bit of extra cleaning up on the newly applied texture, namely on the edges of the tree. 

And the tree is done!  Now this can, of course, be used in parks or natural environments without the need of a Christmas theme. 

No need for the guide lines anymore.  After you remove them you might want to still move a few of the lights around just a touch if it helps improve their layout. 

Step 4

We'll make two types of ball ornaments.  They should be pretty tiny circles—these are 2x2 (interior pixels) and 3x3. 

I liked how warm colors looked against my tree, so I went for these gold and copper colors. 

Step 5

Place the smaller balls on a New Layer, below the lights layer. 

They should look random enough but without leaving big open patches or clashing too much with the lights—find a balance! 

Step 6

Now substitute some of the balls with the larger balls. 

You could try changing the hue on them or adding a greater range of colors if you want.  I felt like keeping it simple. 

Step 7

Let's soften the outlines of the balls, except for when they're right on the edge of the tree. 

To do this you can select the shades of green on the tree layer (Magic Wand Tool again) and then go back to the ball ornaments' layer and use the Paint Bucket Tool (with contiguous checked off) to color the outlines with a very dark shade of green.  The areas of the outlines that go past the edges of the tree will stay black/nearly black, and the outlines inside will still be dark but will remain more harmonious with the tree. 

Step 8

To finish the ball ornaments off, we'll apply some shading on them, similarly to how we did it for the cone.  Here in white I've selected the balls that will be a bit lighter, as they're in the brightest section of the tree, while the black ones will be darker. 

Step 9

To make the changes, you can select the balls you want to change (only the interior pixels) and play with the brightness and contrast (Image > Brightness/Contrast…) or with the saturation and lightness (Image > Hue/Saturation…), or simply hand-pick new colors. 

The effect is subtle, but it does help to convey more volume. 

Step 10

And now to top the tree off: the star topper! 

Here's our very tiny star, outlined and then filled with a nice bright yellow. 

Step 11

We'll place it on the tree right over the top, of course, but let's add an extra effect to make the star pop a little bit more.  Add an extra outline of a high-contrast color which we'll later replace with the same Christmas tree light color at 50%. 

Done! 

Here's the finished tree, with some background color to help viewers appreciate the light effects.  Feels nice, warm and fuzzy… like a certain holiday!