Nootropics also known as smart drugs are well-known compounds or supplements that enhance cognitive performance. These compounds are work by enhancing brain functions such as memory, creativity, motivation, and attention span . There are two types of nootropics that can be synthetic and natural (such as Ginko Biloba, Panax Ginseng).
Natural nootropics have been proven to boost brain function while at the same time making the brain healthier. These chemicals usually act as a vasodilators working on the small arteries in the brain resulting in increased blood flow to the brain and at the same time providing important nutrients that results in increased energy and oxygen usage.
The human brain despite being just 3% of total body weight, it receives a large volume of blood supply, approximately 15% of the body’s blood supply and oxygen are used by this organ. The brain’s main nutrition source of energy comes from burning glucose, this makes our neurons dependent on the provision of a continuous supply of oxygen and nutrients.
Being a Pharmacist and medical student i personally used such nootropic agents to help me work better and study more effectively. The main ones i felt helped me the most include Nicotine, Piracetam, Rosemary and exercise. although we dont know the exact mechanism of action of how these tend to effect the brain studies indicate that they might enhance brain function. I will try to explain further how these agents tend to work.
Piracetam is a widely used medication that is usually given to treat myoclonus and memory enhancement in conditions like dementia and cognitive problems. Piracetam in pharmaceutical terms is classified as a Racetam, a class of drugs that act by enhancing cognitive function by effecting bloodflow and neuron function without the problem of stimulation or sedation. Piracetam has not shown to have any side effect of concern and maybe beneficial at improving bloodflow to the brain and enhancing neurotransmitters like AcetylCholine. The combination of Piracetam and Choline was also shown to have an even greater effect on memory function combined then with either drug administered alone. 
Now this is delicate! in this case i can’t promote the use of nicotine or tobacco products as smoking actually causes a loss of brain function and increases the risk of stroke and cancer. However synthetic forms of nicotine administered in the form of a patch might have beneficial effects of memory enhancement. Agian the way in which nicotine is administered is important as is the dosage. Micro dosing with trans dermal patches might have a slight beneficial effect on memory enhancement and neuromodulation. the only problem i see with nicotine (NOT Cigarettes) is its potential to addiction. 
Ginkgo is a plant extract that is obtained from the dry leaves of the maidenhair tree. Although there is no conclusive evidence that ginkgo has beneficial effects on the memory function, having high levels of antioxidants and flavonoids it seems to protect brain aging as it acts as an antioxidant agent. Ginkgo is usually given in the form of Capsules, tablets and liquid extracts and might take time to see and effect. usually, it takes around 4-6 weeks to see the effect on memory function. of course, taking just Ginkgo alone will not produce notable effects. hence a healthy lifestyle and plenty of vegetables and exercise are vital to see improvements.
Exercise can also help improve neurogenesis (development of new neurons) in parts of the brain related to memory. this might be the result of the formation of BDNF (brain derived neutrophic factor). This Factor is important at it improves the vascularity and the promotion of new neurons in the brain, especially aging brains.
The consumption of chocolate, especially dark chocolate has been associate with enhanced brain function the reason for this is that chocolate of a higher percentage purity > 75% has a greater level of cocoa which is rich in polyphenolic compounds. A type of polyphenolic compound presented in plant-based foods that is present in chocolate are flavonoids. In one study a Flavonol-rich cocoa drink was given to participants for 8 weeks and the level of cognitive function in adults with memory decline was measured. The study proved that the consumption of cocoa rich flavonoid drinks for 8weeks enhanced the memory performance and reducesd the decline in memory function.
other sources that are abundant in flavonoid compounds also include tea, coffee, red wine, grapes, nuts and seeds. As with this study, other studies also showed that there was a positive association between flavonoid consumption and reduced memory decline.