Texture in oil paintings

There are several methods to give texture in oil paintings like impasto and many more. You can check details easily through search engines.

if you use a finer brush or play with a palette knife, both of these are quick ways to do impasto. A finer brush, when loaded up can leave a lot of paint behind.
Then also, don't thin your oils out ,except for white, I always like to make my whites more like ketchup and everything else like jelly and apply whites and really light colors LAST.

I always do a canvas
Left to right and
darks to light