try out = (1) test to see how useful or effective something is

e.g. He tried out his new bicycle as soon as it arrived.

try out = (2) compete for a position in a team or a part in a play

e.g. She tried out for the school netball team.

try on = to put on a piece of clothing to find out whether it fits you or whether you like it (Notice that two other phrasal verbs have been used in this definition.)

e.g. I tried on several shirts before finding the right one.