Have you seen the kids when they draw or paint? they used to pressure really hard on the piece of paper or canvas, they looks like pretty secure about what they are doing.
In adults is different, some have really hard brushstrokes other very soft like they were very scare of the canvas, the point is you need to control as you wish if you want to really go with hard brushstrokes over your canvas or very soft.
We must have a great command on the brushes we use and the proper pressure when applying the oil paint, glazes and fading will be of utmost importance for the finish of our paintings, This pressure must be cultivate with practice, to begin with I recommend practicing with pencil and then practicing with brushes.
I have done this exercises with my students and they get result really fast. Because it is very simple, you just need to realize that you will get the best from your brushes if you know how to control your own hands.
The first exercise is to reproduce the scale of tones with a soft pencil, use very soft pencils numbers 8B or 9B, charcoal soft or charcoal, you must repeat it several times, let say once a day for a week, this will help you to control the pressure for the lighter areas and force them to press hard in the dark areas.
It must be done in a single stroke do not stroke over several times, it means that you need to pressure really hard for the dark values and very soft for the clearest values in this way you are pushing your hands to dominate the strong of every stroke.
The next exercise is to paint a sphere, you can first cover the whole sphere with black then apply a little white on the area of light and fade, or apply the dark and white separated and then blend the tones.
Do everything with flat and smooth brushes, must have a separate brush to integrate and blend the oil, at the end can pass a brush fan to smooth the surface even more.
Repeat this exercise several times, combining both exercises will allow you to improve the pressure of your brushes over the canvas in not time.