First Things First

This is an interesting graphic that I stole/reproduced.  Far too many people are obsessed with the upper levels of this pyramid without having a lock on or even an understanding of the foundational layers.

Energy Balance: Are you eating the right amount of food?  Enough to fuel workouts? At or near maintenance to keep your fat in check? Below maintenance for limited periods to promote fat loss?  Do you even know what maintenance is FOR YOU or if you hit it on any given day?

Macronutrients: Assuming you are in Energy Balance, do you get enough protein? Do you eat enough carbs to fuel your activities?  Enough fats to stay healthy and sane hormonally?  Are you slavishly following trendy diets which eliminate entire macronutrients or which are based on 50 year old science that has been recently debunked/moderated?

Micronutrients: Assuming you are in Energy Balance and are getting the correct ratio of Macronutrients, do you eat a wide variety of whole foods including lots of colorful vegetables?  Do you get enough fiber to support a healthy microbiome? Are fermented foods part of your diet at least weekly?

Nutrient timing: Assuming your diet is in balance, composed of the correct ratio of macronutrients, and contains a wide and complete mix of micronutrients, are you ingesting the most beneficial and energy appropriate foods before, during, and after your workouts? 

Supplements: Given a thorough understanding of all of the above, are you intelligently filling in any gaps which may exist with proven nutritional supplements?

If you're fat, tired, and not making gains in the gym, do you really think a protein shake and creatine are going to help?

I would also argue there's a layer missing in between nutrient timing and supplements, which to me is where you shift from food to pharmaceutical intervention so to speak.  "Recovery".  Are you keeping an eye on mobility (especially as you age)? Are you sleeping enough? If you are otherwise active, are your recognizing that day to day activity and recreational pursuits can start to impact your performance in the gym and vice versa?