Although prices are competitive with those from other manufacturing countries such as China and Thailand, Malaysia still wins in terms of quality control at the low prices.
However, if you intend to be doing some mountain-climbing (there are some interesting places, including the highest peak in South East Asia located in East Malaysia), hike/camp in the national parks, etc. Then an almost-empty backpack would be more appropriate ... again, you can stock up with everything from 'Tabard' (the essential rub-on mosquito repellent .. you'd be thankful for having it when you enjoy going to open-air stalls or walk around at night for extended period, or for going into parks, rainforests, etc.) to other necessary gear, when you arrive in Petaling Jaya, or any other town/cities in Malaysia.
For what is appropriate to wear here: loads of sunblock, a pair of sunglasses, hat/cap if you prefer that to holding an umbrella under the scorching sun, a towel/handkerchief/plenty of tissues and/or anti-perspirant for the inevitable sweating sessions, light clothing - from short skirts, sundresses, vests, cullotes, to shorts, t-shirts. In the day, you may walk around in shorts and sandals (even in shopping centres). However, for some for exceptional restaurants, nightspots, libraries, etc., casual t-shirts, vests, and sandals are not allowed. For classical performances, ballet, etc. you are expected to be at least semi-formal in attire. To allow for smooth transition from day to night, jeans, t-shirt, and sneakers as a combination can usually get you around most places. With the weather, an umbrella in the bag is always handy for rain or shine.
You can get all the toiletries and medical supplies here cheaper than anywhere else (I'm serious! most of them are manufactured here anyway!). But get the kind of jabs/immunisation that you need for coming to this part of the world such as for hepatitis, etc. if you plan to be eating at roadside stalls when you're here or any other roadside stalls of countries in the Asian region.
Get it all here! You can sometimes find electronic/electrical goods that you've purchased from your home country 'Made in Malaysia' anyway. But if you already have one, bring along a digital camera (you can buy more memory cards and spare rechargeable batteries here), or if you still like the traditional automatic cameras with APS or 35mm film, you can develop the films and buy more films cheaper here than in developed countries :-)
You can actually stock up on these gear here in Petaling Jaya! PJ Uniform shop in SS2 has some camping/outdoor stuff because most scouts/girl guides/rangers come here for their supplies, but if you intend to get even the heavy stuff such as tents, etc. you can head on to bigger departmental stores/shopping centres such as Parkson in the Atria shopping centre (in Damansara Jaya residential area), or Jusco in 1 Utama (Bandar Utama residential are) - you can find beach gear in Parkson and Jusco at good prices too. You won't be able to bargain, but you can look out for sale items. Feel assured that apart from morning/night markets, these are places locals go for shopping for bargains and reasonable prices too.
It might be handy to get yourself a guidebook hopefully with some transportation information (e.g. bus routes, LRT routes, maps), some common phrases in the national language of Malay (simply to 'wow' the locals and break the ice, as many locals are apt in English anyway), and more details on all the states of the country if you might consider exploring the country further.
