The phrase "trying on" can be used to describe the act of testing or experimenting with something. There are a few other synonyms you can use depending on the context. For example, "sampling" is a great alternative when referring to trying on clothes or tasting food. "Testing out" can be used to describe trying out a new product or exploring a new idea. "Experimenting with" is another option when looking to describe the act of trying on something new. Finally, "trialling" or "experimenting" can be used in a professional or academic context to describe experimenting with different methodologies or hypotheses.