[ 1. You get what you pay for, at least for all the mainstream notebooks. Much like everything else in the market, if you pay peanuts, all that you're going to get are peanuts. Most Malaysians tend to ask for notebooks with the best "bang-for-buck" or best performance for the price, which is not exactly a very viable option. There are many other aspects to look for in a good notebook (Point 2).
astria sifu once said: "They must've cut corners somewhere you don't see it to achieve such a low price."
lil kiasu: "Cheap no good, good no cheap."
2. Don't just look at the main specifications of the notebook (CPU, GPU and HDD). There are many other aspects of a notebook that you should look at, for example:
- do you like the design of the notebook?
- How’s the warranty support for this notebook/brand?
- is the keyboard comfortable to type on?
- are the speakers good?
- is the audio/mic ports combined or separated?
- is the cooling system good?
- is it easy to access the inner parts of the notebook (For upgrades and maintenance)?
- does the touchpad suck?
- and a whole lot more etc. etc. etc.

Of course, there are a lot more points to ponder, and each person has a different priority in the features they want. Which is why we sifus always recommend potential buyers to check out the notebook before buying. If you are a gamer, don't buy a very powerful machine with a very bad cooling system! It's not going to end well...
In short, you don't need a notebook with the most powerful CPU or GPU for your budget, you need one that you like (design and ergonomics), one that fulfils your usage.

3. Don't buy based on the brand. People tend to generalize when it comes to brands- If his/her notebook sucks, then everything from that brand sucks. This is of course, inaccurate.
One has to understand that there will always be lemon units in electronic devices. Whether a notebook lasts or not depends on a little bit of luck, but a lot on user care!
Even the most premium brands out there are not free from defects.

"Is Asus or Lenovo better?", we get this kind of questions a lot.

Each brand has different lineups of notebooks, ranging from budget to premium to workstations to business notebooks etc. Of course, don't expect budget notebooks to be extremely reliable, and don't expect business notebooks to be cheap. Each lineup of notebooks were designed specifically to suit different niche of people.
Thus, know which category of notebook you are going for, and set your expectations accordingly.

4. Buy based on warranty support. Apparently after sales service wasn't a really big thing 2-3 years back, but things have changed. People now understand how frustrating it can be to send in their faulty notebooks to the respective shops/service centers themselves, then wait for up to 2 months laptop-less for repairs. And that's not it, some might even have to put up with bad customer service or recurring faultiness. In the end they wasted a lot of time, money and effort, and sometimes the notebooks aren’t even fixed
We are fortunate that some brands in Malaysia (Dell, Lenovo, HP, Toshiba, Fujitsu) took note of the problems we customers were facing, and provided on-site warranty support (they come to your place and fix your notebook within 1-2 business days) for certain lineups of their notebooks.
So far, only Dell offers on-site warranty to all their notebooks, with the option for warranty extension. This is a package that I would highly recommend to everyone, particularly students who do not have spare notebooks.

5. Do your research before buying. If you are reading this, then good for you. It's good to read up a bit on the notebook(s) you are interested in before you make the purchase. Not every notebook is perfect, each one will have its flaws, so it'll be good to read up reviews on them as well, and decide whether the drawbacks will affect your usage and ultimately your purchase.

Words of advice: (i) Avoid buying a newly released product which doesn't have any reviews yet. You might end up getting a notebook with universal problems (as in all models suffer from the same issue) which will give you a big headache. (ii) Avoid getting limited edition notebooks that are specific to a specific region of the world (South East Asia for our case), you will have problems getting proper warranty/technical support and spare parts.

6. Always compare Apple vs. Apple, Orange vs. Orange. This will probably earn me some hate from the fanboys, but if you are going to compare an Apple against a Windows-based notebook, please compare those of equivalent price-range or niche.
Too often do the sifus hear Apple users complaining that Windows-based notebooks are rubbish because apparently their RM1000 Windows netbook suck and their current RM5000 MacBook works miraculously well We sifus have no qualms with you comparing notebooks of different operating systems, as long as you are fair about it, and you are not spamming the thread with bashes and hate. However, whichever operating system/brands you choose, please do remember to take note of Point 2 and Point 4.

7. Shop people don't always know everything. In fact, I've only seen a handful of really competent and knowledgeable sellers in Lowyat plaza or during PC Fairs. Most of the shop sellers are part-timers trying to make a living, unlike the passionate forumers (not me, I'm actually a so-so @__@) here who follow up on all the technological advancement just because they love it.
Shop people will say virtually anything, as long as you buy from them at the end of the day and the commissions go into their pockets. So make sure you do your homework first before you buy anything, unless if you don't mind being ripped off la But worry not, for we are here for you haha~