How to find out if a bitcoin mining pool is working?

Could you elaborate on how an individual or investor could verify the effectiveness of a Bitcoin mining pool? With the volatility of the cryptocurrency market, it's crucial to ensure that one's mining efforts are being utilized in a profitable manner. What metrics should be considered? Are there any specific tools or websites that offer insights into the performance of various mining pools? Additionally, are there any common pitfalls or mistakes that one should avoid while evaluating a mining pool's efficiency?