The start colour still shows in this project. (the initial base yellow represents the lightest tone of the faux simulation - #1). Dragging and flogging of subsequent glazes (#2, #3) deepen the tone and texture. A fitch was used for the final overgraining.
Acrylics dry quickly outdoors, hence the need for a quick hand and a good mental picture of the proposed graining. Making a pencil sketch of the layout is helpful to look at, as are having close-up photographs of real wood graining.
As an artist you may prefer to pre-sketch the surface using a water-soluble lead pencil (the lines will get washed away in the course of your work).
I've used masking tape to demarcate each board. The taped edges should be sealed to prevent leakage.

The spritzer water bottle (on the doorstep) is handy for keeping the glazes damp and workable on hot and windy days.
This door was done with artist's tube acrylics. A metallic bronze acrylic made the oval frame a decorative feature.
The dog was not easily amused.
