They work sometimes, but you are better off understanding why they might work, and building something for yourself.

So, the reason that there are pre-workout protein shakes and post-workout protein shakes are:

Pre-workout - dual purpose of providing bio-available energy sources for your body to burn during the workout and increasing the amount of amino acids in the blood. Higher amino acid levels in the blood during a workout does two things. It discourages muscle breakdown and encourages the production of human growth hormone, testosterone, and muscle.

Other things that are typically in pre-workout shakes are caffeine, which increases blood flow, thus increasing oxygen delivery to muscles and helps with energy production. They also typically contain b-vitamins, herbs, and other things that are intended to help a person focus on the lift. They also typically contain creatine, which can serve as an energy source during a workout, but must be absorbed by the muscle prior to being available for energy. Therefore, there is no advantage to taking creatine immediately prior to a workout. Instead, you should take creatine every day to saturate your muscles with creatine. It doesn't matter when you take creatine, only that you take it regularly.

There is some advantage to the protein and amino acid exposure, but if you do a cardio warmup, or if you do Crossfit style workouts or you minimize your rest time during lifting so that you heart rate is elevated throughout the workout, caffeine can raise your heart rate to an unhelpful level. I also know lots of people who are dependent of pre-workout shakes in order to lift. I take about 1/2 a scoop (10g) of a cheap protein and a scoop of an amino acid powder.

Post-workout - lots of people take a post workout shake under the idea that protein synthesis, human growth hormone presence, and testosterone presence are higher during a window of time immediately after working out. Sources are split as to whether this post-workout window is a thing or not. I'm not convinced that it is, but I still take a post workout shake immediately after my workout because I substitute that for breakfast on my way to work. Post workout you really have two goals-increase protein and amino acid availability in the blood so that your body has excess materials available for muscle production and replenish depleted energy supplies. Therefore, you need three things post workout- lots of protein, amino acids (I take branched chain amino acids), and glucose (sugar, or carbs). I get my protein from a higher quality protein source, mixed with whole milk. I take some BCAA pills, and I eat a banana. I prefer to get my glucose from a natural source, but some get it from other places. Some people stay clear away from all sugar and fruit sources. These people don't understand that sugar is necessary for muscle function. A depleted glycemic system will result in weakness. People lose a lot of weight by completely cutting sugars and carbs out of their diet, but it is detrimental to performance.

As for what supplements to take, check out labdoor.com. They are a third-party testing group that rates supplements. Based on their reviews and lots of trial and error, I use Optimum Nutrition brand supplements almost exclusively. They are a good balance between quality, cost, and availability.

I'm happy to answer other questions.