Something like Piracetam, and any of its close relative -acetams that have been well studied are a decent choice. I'd stay away from the more exotic -racetams, since they haven't been well studied and no one honestly knows what might happen. The one thing I'd say about these is that if you have a headache after taking it, your dose is too high. Reduce your dose, keep doing this until the headache goes away. If it doesn't go away after getting to a low dose, just stop taking it, some people are sensitive to it/more prone to headaches. As far as the more exotic -racetams, one reason to avoid them is that some of the -racetams actually act in the inverse of what you want, they inhibit or dramatically slow neural transmission. They are actually used as successful anti-epileptic agents (prevent seizures/fits) because they slow down neural activity. So, if you start messing with the exotic -racetams, you may actually end up with one that works inverse to what you are interested in.
Sulbutiamine is another interesting one. It's a thiamine (Vitamin B1) dimer, approved as a medicine in France and Japan. It has been shown to increase neruometabolic activity by making thiamine more available to the CNS. Being a simple vitamin dimer, it's basically harmless.
Choline Bitartrate is a good one. It's actually an essential nutrient, and basically no one gets enough in their diet. It is the basis for the synthesis of the neurotransmitters in the brains cholinergic system. So, essentially, taking it is just ensuring you have enough building blocks to keep the cholinergic system in your brain working at optimal efficiency. Choline is essentially a "food" molecule, so it is completely harmless.
As far as diet, make sure you are getting sufficient EPA & DHA. These are essential fatty acid nutrients that your body needs to build and maintain neural structures. Low levels of both are linked to a large array of various neurocognitive issues.
L-Theanine is not a nootropic in so much as by itself, it does nothing for cognition. When combined with caffeine, but more so coffee in particular, it works in synergy with it so you get all the benefits of the stimulant properties of caffeine with regard to neuroprocessing, but none of the negatives, such a jitteriness that can occur for some people, because that is handled by the L-theanine. You can think of L-theanine as more of a complimentary caffeine/coffee enhancer.
I say say this with absolutely GIGANTIC caveats, but there is some preliminary research that microdosing with Psilocybin can be beneficial for some people, but I absolutely do not endorse trying it. There is just too much unknown at this point.
Other than what I mentioned above, the majority of the stuff either hasn't been well studied, interacts with common food/medications, or has a thin margin between what is effective and what can injure or kill you.