uchihaMadara
Personally,
1) adequate sleep helps,
2) supplementation with
a) magnesium (citrate, malate, glycinate),
b) SSKI,
c) seleno-methionine,
d) B-complex (active/natural)
3) diet
a) natural/organic foods
b) avoiding/reducing garbage
c) juicing (carrots work magic, for example)
4) reduce stress (all/most stressors)
5) change environment if un-focused
6) plan what your concentration goal is exactly and continue until you've achieved it or are satisfied with the result(s)