Mate you need to do some readin or you'll end up with gyno (man boobs).
Here's a quick summary:
Deca + sust = testosterone (male hormones)
What happens is ya male hormones do the good thing and help ya get huge and all. But at the same time ya body tries to balance out and starts making estrogen (female hormones) witch is ok while your testosterone is higher but once you finish your cycle your male hormones drop while your body's still making estrogen. This is where pct comes in (stop man boobs from growing) There are a few drugs out there that stop estrogen in its tracks.
I personally use clomid 50mg a day for about 2 weeks after the end of my cycle.
My advise is while on cycle train as hard as you can, and don't be scared to push ya self to your limits and "get your hands on some anti estrogens quick".
good luck