Food timing and hydration are both important to the quality of a workout. A food program will complement any workout because there is fuel in the tank. Always start with a solid food program and build a supplement arsenal around it.
Plugging in a supplement for a specific reason could enhance a workout. Pre-workout, carbs and aminos may be a great addition for energy, power or pump before a workout. Carbs or amino may be a fuel source for energy or endurance during a workout. Protein, amino or an MRP could aid in recovery for a post-workout drink.
Different goals would determine what supplement to use. Fat Burners, carnitine, CLA could be a nice addition to a leaning out program. While a weight gainer and carbs would compliment a weight gaining program.
Athletes would make specific supplement decisions based on the performance they expect. Endurance athletes and/or events would benefit from carbs, aminos, and protein. Where a strength athlete may be better suited to use pre-workouts, aminos, carnitine and/or protein.
Lack of energy. Lack of pump. Lack of focus. Lack of hydration. All these challenges can be specifically addressed with the right food or supplement.
Work with a knowledgeable trainer. Log workouts, food, and supplements. Get cleared from a medical professional.