To minimize space, I keep my stuff on zip lock bags 
One thing I get better every time we tour is packing. I always eliminate one thing I brought after the previous tour, thus saving lots of space in my bag for other important stuff like pasalubongs and souvenirs.
Zip lock bags plays an important part in packing items in my bag. You get atleast 40% extra space on your bag when your things are tight in these zip lock bags.
Before, I would only zip lock my undies, but since these things are efficient, and reusable… I started zip locking almost all my items, even my shampoos! hehe.
I zip lock my clothes depending on usage – all tops goes into one zip lock bag, all bottoms on another, and all undies in another one. I even zip lock my towel, it could be worse if it gets wet.
Gadgets such as cellphone, and ipods are also zip locked. You would not want items like that to get wet. hehe. I also zip lock all personal grooming items like deodorant, shampoos, cotton buds, etc. Its not that I’m afraid they get wet, its just easier to locate these things in your bag, if it’s all grouped together.
Also one rule we have with packing, is to bring thin-cloth shirt, and shorts.These type of cloth is not as heavy as regular ones, and it will not be as heavy even when wet. So even though our get up does not look good, its better to sacrifice beauty than strength when it comes to touring, hehe.
With regards to towel, some of my friends just brings their sarongs to dry up, it has so many uses other than drying yourself. But for me, I still prefer to bring towels due to my long hair. Though my towel is not the big towel you normally use at home.
Every tour, there’s always that one thing that I regret bringing or not bringing with me. Like this one time, everyone brought slippers with them, and I was the only one who didn’t. I wore my sandals from the bathroom to just every where we went to. I kind of regretted not bringing one, so on our next trip, I brought slippers with me, and everyone else didn’t, haha. So the lesson there is, bring what is comfortable for you. In this case, its much better not to bring an extra slippers if you have a sandals already. You can save an awful lot space on your bag 
At one point, I was the only who brought slippers with me
By the way, it may sound like Im over compulsive, with how super organized my bag is. I just have learned my lesson when it comes to packing my things. You should see my regular bag, it looked like a jungle in there. hehe.
