* Noise cancelling headphones. Especially useful with no music playing through it. If music, ambient or techno without words seem to help depending on what I'm doing.
* Understanding your most productive times of day and taking advantage of them (for me, its the morning. Afternoon is the worst)
* Reducing all distractions as much as possible. Turning off WiFi, putting your phone on silent (or better, keep it in your bag out of sight) really helps.
* Making lists. Breaking things down into smaller tasks that I can see myself completing and then giving myself small rewards for completing them.
* Rest and daily exercise is a BIG DEAL. Exercise especially helps my willpower and ability to stay focused throughout the day. Try Yoga!
* Natural light keeps me feeling fresh. Artificial light wears me out.
* Take walks on your breaks, avoid surfing the internet or extra stimulation... doesn't help and makes focusing even harder.
* Marijuana. Low doses of indica dominant strains either via edible or smoked helps keep me locked and focused way better than any stimulant drug.