Maybe you are getting bored of these videos by now? Well suck it up as I am about to post another :D
This is a really quick little example of my process including adding texture. I mainly achieve most of my texture through brushes and how I use them in particular. The only advice I can really give is to experiment as much as you can. The more you play with brushes the more you will realise the extent of their ability. You will gradually become very comfortable with a brush set and with a bit of patience you can create some really beautiful marks and textures.