Hi jasphotography,
Just curious, which part of sumatra are you going? In general, in indonesia, just try to blend in and try not to speak too much since people will know that you're not local or have not stayed here a long time.
Dressing probably should be more casual, dressed down.
Yes, please beware of pickpockets and people around you...
Try to hold on to your bag at all times (can get something like a sling bag) and make sure you can see it at _all_ times.
I've never really taken taxis there before coz my relatives there have cars
but you might want to try the trishaw (they call it bear-cak -> according to pronounciation but again it depends on which part of sumatra you are going again). Can bargain with the driver to say how much you offer....
yea heard of stories about the taxis.... best way is to get someone who knows their way around and speaks bahasa indonesia so that he/she can keep a lookout for you. If you can go in a group, it's always recommended (especially so for females!).
For taking pictures, think it's still okay but dun take too long like setting up tripod or stuff (if you do then get people to keep a lookout for you). Try to keep low profile and try to act as local as you can (especially helps if you speak the language). Take pictures quickly and ya don't use equipment that look too expensive (you can always make it look more shabby or something).
the traffic conditions there in general are crazy so be very careful and alert. Try as much as possible to steer clear of dark places. Walk briskly.
Think rule of thumb is try not to travel alone, if not then don't act as if you don't know where you're going. Indonesia is quite a beautiful place and it's not _that_ bad. You just need to stay alert and keep a lookout.
There'll be beggars but _don't_ start to give them money coz all will come to you when they found out that you give to one (unless you're protected in a car). Don't display your money in public too. You don't need so much to get around there...
The chinese people there (if any) are generally more friendly since they're chinese too.... and you'll have a better chance of being understood since they'll probably know some english or chinese.
Btw, handphones and cameras there can mean like years of pay to them.... not months so that's alot of money to them...