- Indo Airlines rarely weigh carry-ons or comment on the number of bags (locals travel with lots!) and so the advice to load them up and pretend like they don't weigh anything is a good idea.
IME the SE Asian airlines love to charge the foreigner who has a couple of kg over the limit but turn a very blind eye to locals who are bringing their entire house with them on the plane- including TVs etc. I am usually a few kg over and I usually have to pay- and sometimes it's very expensive.
Malaysian Airlines is pretty good for giving extra allowance for diving equipment- it's one of the few airlines that do. If I can I always fly with them. Good planes, good service and an allowance on diving equip. (you must contact them and have diving license on arrival).
The last advice is usually the best- aim to be the first in line to check in. As the plane starts to fill up the check in people get stricter IME