Best tips to stay focused?

I can't focus no more for today...

try to nap somewhere for an half an hour?

Stop and do something else.

I know this problem. Go outside, drink enough water, less sugar and less caffeine.

Having this feeling today, too. Although I have a test for a job to do and send over. Fml.

Listen to some chillout music (I like the MixHound livesteam on Youtube), drink a glass of water, open windows to get fresh air :)

Do something else and relax for awhile.
Hyper focusing (or being "in the zone") burns expensive neurotransmitters; they take awhile to replenish. Caffeine here is very counterproductive.

After you've recovered and relaxed, begin to review data about your project, think of what it needs to accomplish, and the first steps to doing that. Start planning them, and soon you should be back "in the zone" again. Caffeine helps!