I recommend to you this book. It is something that I always refer back
http://cgi.ebay.com/Marijuana-grow-basics-Jorge-Cervantes-/160433445803?cmd=ViewItem&pt=Non_Fiction&hash=item255a941bab
along with The marijuana grower's bible also by Jorge Cervantes.
So much useful information. If you don't want to spend alot of money. You can surf these boards like the others suggested. I just would be wary of the advice you take from here because some of it is completely off base and might send you in the wrong direction. With the books you can know that you will be successful if you follow it. HOpe this helped
To increase bud weight...depends on what you medium you are growing in....Hydro? soil? outdoors? indoors?
If its Hydro indoors any supplement from the General Hydroponics line is great. Kool Bloom is an awesome 2 step supplement. Advanced Nutrients as a variety of supplements that can get some amazing results. Fox Farms also has a great line of supplments. It really a matter of choosing a line of nutrients you like and sticking with them and perfecting or dialing the nutes in right where the plants love it. Hope this helped.
PEace and positive energy to you.