It depends on the type of master's degree that you obtain. A master's degree in experimental psychology will benefit you if it provides you with quality research opportunities. Plus, compared to applied degrees, they are not as heavy in the assessment and therapy courses which may be a plus in the eyes of some PhD programs because they want to form you from the beginning in their style of clinical practice.
However, you should still consider a master's degree in clinical psychology. Some of these programs are research-oriented. Granted they're uncommon, but they exist. Many master's programs in clinical psychology claim they can prepare you for a PhD, but don't believe it without evidence. Some programs provide consistent information about their alumni outcomes, which is a sign that they deliver what they promise.
Many people advise volunteering on a research team at a local university instead of a doing master's program, because they can be expensive, but sometimes you can't locate quality volunteer opportunities locally. In this case, a research-oriented master's program can help you put your foot in the door of a productive team.