Hi! Thank you so much! About your question; I'm assuming that you are using some kind digital drawing tablet, if so, make sure you have control on the pressure you apply to it. I dont really do anything fancy with my opacity and flow settings in Photoshop. Most of the time I keep them at 100%. Why? Because the tablet has more than 2000 points of sensitivity which will help me blend colors.

As to how I blend colors I think its rather simple. Take color A. Then, with a soft edge brush, paint over color B. Then, take color B and paint over color A (this is basically the same way you would do it traditionally!). Also, always take into consideration your light source and what kind of material you are shading. Hard directional lights will cast hard shadows that will not need a lot of blending while soft point lights will need a lot of blending. I hope that helped! If you have any other questions send me a DM :)