The adjective advantageous is useful for talking about things that are beneficial, or helpful, like when you find an advantageous spot to hang your yard sale sign — a spot where all the passing cars can see it.
Anything that creates an advantage is advantageous. You could describe your decision to throw a huge party as advantageous for your social life, or the cooking class you took as advantageous to the success of your catering business. If it helps you get what you want, or is generally useful, it's advantageous. The root is the Old French word avantage, which means "advantage, profit, or superiority." Anything that assists in your pursuit of these things is advantageous to you.