You can't expect to manually find focus every time with f1.4 it's impossible to do even by seasoned professionals.
First, put your camera in autofocus. Then fine tune the lens focus from the in camera menu, using a ruler in various distances, and trying focusing on a certain value.
For example by focusing (auto) at the number 5 of the ruler and then opening the image and looking it at 100% you can understand easy if your af frontfocuses or backfocuses. So then apply finentuning adjustments from the camera menu until your focus is sharp where you need it. Do this for all distamces, close medium far.
So after this you can also increase dof for example.shoot portraits at 2.8 or 3.5, you can still get a nice blurry background but more sharpness out of your lens because you stopped down to the point that is 2x your lenses most open value and ia usually the sharpest setting on a lens, which lasts until about f8-f11 before having the sharpness quality drop slightly.