Gradients in substance painter can be complex to do if we don't use the right tool, for this example we are going to make a gradient from red to gray in this character's pants.

To start we will need to have the position map baked, If it isn't, you can bake it directly in substance painter.
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We start by creating a fill layer on top of the base color layer.

We create a mask on the gradient layer and add a 3d linear gradient generator.

Inside the generator we have the options of 3d position start and 3d position end, for the gradient to work correctly we have to pick the color of the model's position map.

When we return to the material display mode you will see the result of the gradient.

Baking lighting is a very simple and very useful process that can help us to highlight parts of the model and if the final model is not going to be affected by real lighting it can provide a more realistic touch.
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We will start by creating a fill layer with the properties that we want to give the light to which we will add a light generator.

Inside the generator we will find the properties of the generator such as the direction and the height or the intensity.
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Once we have everything configured to our liking we will have to change the layer fusion option in case the light can work well with overlay, soft light although the best way is to try which one best matches the result we are looking for.

The anchor points are used for the intelligent masks to detect deformations of normals made in other layers that are not mapped to the normals map.
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In this example we have a layer with height and we want the mask that we are going to create next to paint the borders automatically.

To solve it we must enter the options of the smart mask and modify some attributes.
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The first is in microdetails change the first two parameters to true the second is at the bottom, in Micro height, there we select anchor points and look for ours (its recommended to name the anchor points correctly) after doing this everything should work correctly.

The roughness map is one of the necessary ones in a PBR material, and also one of the most important when it comes to giving detail to a model, so it is important that in the PBR models the roughness has work and detail.
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In the first image we have a model with a practically flat roughness, in the second image we have the same model with a much more worked roughness.

To achieve these results we can use smart masks, occlusion and curvature masks and of course textured brushes to give wear details.
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Although it may seem very basic, the brightness changes of a material are what help to give a model realism.

Before opening any 3D software, we look for references and place them together...

• To get a grip about the feeling we want to convey.
• To establish The overall shape reference.
• To define a good looking topology.

When it comes to picking the right colors, I like to visit Adobe Colors to quickly make my own set of color palettes or to create one from the colors of the images from the references.

These are some of the palettes for this project:

To open the project, we can use the default template for Painter since we are only going to use the albedo on this project, but if we want use some opacity to add some transparency on the model I prefer to use the left one.
It's not necessary to decide it right now since you can change it any moment from the shader settings.

It's possible to import the normal maps and other additional maps when you start a project, but you can get a pretty good result from the baker mesh maps in the Texture Set settings.

One of the things I like to do, is to add a Fill layer with a base color without detailing anything to see that the composition works.  At this time, on the project I usually work on the Base color channel since the other channels are not crucial on this moment.

Another thing that I like to do is work with fill layers and paint the masks, that way if you want to change the color to try another tone you can do it easily in the property fill. I consider this one of the good practices in substance so you can leave the paint layer for small details later on. ​

To add some texture to the base color, I duplicate the Fill layer and change the color to a darker tone to see the changes. Then I add a white mask and start to tweak it.

I like to add a generator with a mask editor, since it gives a really good base for a mask, and rise the ambient occlusion and curvature.

Then I add a sharpen filter to harden a little the edges of the color, and finally I add levels so I can invert the colors, here is the difference:

Here is the final the result (without the  other colors): 

Then I duplicate again the base color and chose a lighter color to add some light, I do this by adding a white mask and using the mask editor again. But this time I work with the textures too.

As you can see in the image I put the  first texture on Multiply and the Texture 2 on add/sub, For the textures on this case I used ones that come from substance since it has a great library but you can import your own resources from File.

When I paint I like to add some contrast to the base to balance the output of color, to do this add a fill layer in soft light or overlay and modified it with the light generator, to give it some direction and degradation of it, the light generator usually I leave it on Divide.

For this part I recommend to use a normal layer, so you can paint it over, since you can pick the colors from the base created before with the brush. For the brush itself I usually tweak the flow and the stroke opacity and leave it at half. 

Be sure to check that the two of them work with the pen pressure since by default is deactivated. Then on the properties tab I tend to use the spots brush and I change the alpha to dirty blurry dense. I found this to be one of the best option since is round but without a perfect shape.

As you can see on the layers on the image, the next step is to separate and change colors, dor the final layers, that are on top, the stroke opacity and flow tends to rise up, since the hard lights are on top of the surface. 
Morever, in this case I have to use the blur filter so I coul give the Ice cream the fluffly look to the Ice Cream.

For the rest of the items on this model I applied the same principles explained before. For the chocolate for example I created a Fill layer with a dark color and added a black mask, then I painted with white the with 0% hardness, until I got a ramp of browns as a result. Same with the strawberries.

For the wrapping paper, I used a stencil to write the letters on the paper using a Fill layer with  a black mask, then on the brush I load my alpha and the paint on the position I want.

When you want to work the other maps like opacity or the roughtness, Create another layer that has that one active and the rest inactive, that way you can control better the results without worrying about the rest of the maps.

All in all, Substance Painter is a really powerful tool, that can be used for a great variety of projects. Being able to hand paint the textures directly on the texture sets, different from Zbrush that paints vertex or from Photoshop that does not allow you to see the model in 3D.
​Good tool and Good luck.