Firstly, these tips are not exclusively to all non-Malay/Muslim guests because sometimes, some Malay/Muslims don't seem to know the proper etiquette themselves especially in terms of what to wear.
What should you wear?
Wear modestly, appropriately and comfortably.
If you are attending a mosque solemnization, ladies, wrap a scarf over your head, men, wear long pants. For event places like the void deck, community centre, restaurant or hotel, it is greatly advised to wear smart casual because regardless of the location, it is a joyous celebration for the bride, groom and their family. We want guests to look nice too.
Ladies, please refrain your self from wearing short skirts/dress (above knee length) and any tops that shows your cleavage; pants are allowed. In a traditional wedding, comes in traditional cultures and values. Besides that, wear anything that is comfortable of any colors you want. Usually Malays are greatly encouraged to wear their traditional outfits but if you want to too, we don't mind at all. We love to see your gusto in our culture!
Who can you bring along?
It depends on what is stated in your invitation card. Sometimes it states Mr Bla-bla and partner, sometimes it states, Mrs Toink-oing-oing and family. You can also clarify with sender just in case. Usually, especially if it's a void deck wedding, the more the merrier but of course, within reason. I don't think the bride and groom would appreciate you suddenly bringing your aunties, uncles, cousins and grandparents; unless they were formally invited too.
What to bring?
Bring yourself and a smile.
Void decks can be hot so if you sweat easily, bring tissues or even better, a handkerchief. A small hand fan is acceptable too. Also, a small envelope with some cash as a token of gratitude and/or as a wedding gift to the couple. More on that later.
When is the best time to come?
For the solemnization, usually it's for close friends and family only. Unless invited personally or allowed to attend because you showed interest to be invited, you can just attend the wedding reception.
For wedding receptions, it depends on what is stated on the invitation card too. Some wedding receptions starts at 1 pm while others at 2 pm. It also depends on which side (bride or groom) venue you are visiting. If you want to 'beat' the crowd and settle down first before the newly wed couple makes their grand appearance, come at least 30 mins earlier.
By the way, it's okay if you missed the grand appearance, no one's feelings will get hurt but it's one of the pivotal moments of the day so it would be shame if you did.
How long is the event and must you stay until the end?
Weddings ends at varied timings. The most common is 5 pm or 6 pm but some may last until 8 pm or even 10 pm. You are not obligated to stay up till the end unless you are a close relative to help out or just hang around. Usually, in my experience, guests would usually stay 2-3 hours on average but of course we would love it if you stay longer.
What to look forward for at the wedding?
Frankly speaking, all the happening stuff usually happens at the bride's side. Bride will be seated at her 'stage' as the groom comes in with his entourage and kopang (the men hitting the handheld drums). There will be 'gantries' before reaching the bride and a small singing and silat performance.
If you are at the groom's venue, you can just wait for him to bring his wife over with a simple entrance and cake cutting. If it's combined wedding, you get the best of both worlds.
It's a Malay wedding so expect food and loads of food. Some weddings have photo booths and special food/dessert carts. There are usually karaoke sessions Other than that, just mingle and absorb the atmosphere a Malay wedding exudes.
What should you do when you get to the venue?
Look for an entrance arch or where the wedding favour tables are because that's usually where the bride/groom's parents are. They would formally welcome you and ask you to settle down and eat. Don't recognize the parents? They usually are dressed up extra nice and/or the ones busy hosting and welcoming everyone else. You can always ask around too.
Once welcomed, find a seat, dine, take photos of the bride and groom, dine again (lol), visit the photobooth; if any and sign the wedding guestbook.
Where do you sit?
If it's a void deck or restaurant wedding, anywhere! Sometimes you may have to share with other people but it's okay. Be friendly and enjoy yourself. As for hotels or some community centres, there might be a seating plan so take note of your table numbers.
What kind of food would be served there?
Usually, it's Malay food but in some instances, it may be Indonesian cuisine. Food labels are usually placed for your information. Common dishes are Rendang, Ayam masak merah, Sambal Udang, Nasi Briyani, etc. The buffet are mostly catered for the carnivorous, so sorry there will be a lack of choices for vegetarians. We also have all kinds of modern and traditional desserts too,
Will there be alcoholic beverages served?
I know this is an obvious answer to most but you know...
There will be no alcoholic beverages served and allowed.
Are you expected to give a wedding gift?
Not at all. If you insist, you may but it's definitely not preferred compared to money.
How much should you give to the bride and groom and how to give it?
Honestly speaking, it's all up to you. We don't aim to collect money to match our expenses or even gain profit but if you insist in a number; minimum amount is $10 for people like acquaintances. You may give higher according to your sincerity. We were taught to be grateful whatever amount we receive. In fact, there are people who still give $2 although it's a little silly.
We would appreciate it for you to place the money in a small envelope. It's not a must to write your name on the envelope but if you insist, you may.
How to leave and say goodbye?
If the bride and groom are there and if you have a chance, you may approach or wave goodbye if they are too busy; probably from taking photos with others. Find the bride/groom's parents to formally bid farewell, wish them congratulations, compliments are optional. Preferably, if you are a man, please shake hands with the father and if you are a woman, shake hands with the mother.
Please discretely and respectfully pass them the money envelope. The parents or someone in charge of the wedding favour table will pass you a wedding favour and off you go.
If it is a combined wedding, please pass the money envelope to the the parent's of the side who invited you. For example, if the groom had invited you, please pass to the groom's parents.
I hope my tips and advice helped and if you have any questions that are not mentioned here, feel free to comment and ask!
Update (April 2016):
Photography sessions
Everyone wants to take picture with the royalty of the day but please take note of some protocol and respect. When the couple arrives and after performing a ceremony (solemnization, silat performance, tepuk tawar etc), the immediate families are always first priority in photo taking, followed by relatives/ cousins.
Only after that you may take photos with the couple. Don't worry, there is always time for photos. As long there's and opening, snap away!