First of,what strain....hydro or soil?all details man...
However,you might want to consider a more powerful light..such as a 400..this will make your buds almost double in size..theres only so much you can get with a 150W...seconds if your using soil,consider using mollases..read up on using it..
Its all sugars and carbs to FATTEn and SWEETEn the flowering cannabis...
Other than that..its mostly genetics and techniques.
For example,growing 15 Big Bud clones in a SOG garden under a 600 W light will yield more than growing 10 Big Bud clones under a 400W...