It is best to dress modestly when going around Borobudur and its environs. The whole time I was there, I did not see a single individual wearing short shorts or tank tops. Maybe you can wear your shorts and tank tops inside your room and hotel but not on the streets and in the tourist attractions you're going to be visiting. Most locals dress modestly and follow the prescribed dress code of their religion so it behooves us to be modest also.
Contrary to popular belief, there are no aggressive vendors here. When I was here I only experienced one incident, which was not even aggressive. One dude was already here early in the morning to sell his postcards. But he wasn’t stubborn.
If you don’t want to buy their postcards, just say no, and they will walk away.
I saw a couple of them on my way to the temple. In fact these people were friendly people. They smiled a lot and you could tell they were sincere.
But of course this was only my experience :)
Do you know that more then 40 Million sharks are killed every year! This particulary because of shark finning and the idea that Shark Fin Soup is sooo delicious. If you want to make a difference do not eat in restaurants that offer shark meat or shark fins - since without sharks there will be no life in the ocean.
Still not convinced... do you know how shark fins are taken... the shark is caught - the fin removed and then the shark is thrown back into the sea... without fin!
be careful on the way to the top of borobudur that's called arupadhatu section. the steep stairway can be slippery during rainy season. use the hand rails nearby. and also keep an eye about your own belonging. many times visitors forgotten where they're put their handbag whenever busy taking pictures.
Like it or not, this is how things operate here in Borobudor & Prambanan. If you are an overseas visitor, you have to be subjected to a higher price for the entry tickets (as if flying there wasn't expensive enough).
Under the pretense of national pride, Prambanan costs US$6 pax while Borobudor costs US$9 pax for overseas visitors while The locals enter the park only at a fraction of the cost (almost one-tenth).
Be prepared to be attacked from all fronts by VERY persistent touts (they are there, at the tourist attractions of Borobudor and Prambanan) who will do anything to get your attention and make deals with you to make a sale. Quite a few could tag you for half an hour or so, bugging and harassing you. It could really get irritating.
Keep your calm, do not establish eye contact and keep on walking. Better still, pretend they are not there.
Not really dangerous, but its wise to take care of anything around ya. Sometimes, peoples selling souvenirs will be too pushy. Another time, pickpocketer will take an advantage of the crowded situation around the souvenirs market.
Though the steps in borobudur are not as steep as Angkor , just be careful when you climb up and down on the steps.