I have ordered many items from aliexpress but mostly around 10 to 15 dollars max!
Customs will be an issue if your item is high value and shipping is horribly slow for most sellers.
I have seen even my 2$ order go via customs, not sure what they want to check. lol
Avoid shopping during Chinese festival/other holiday season, your package will be take forever to ship.
Before ordering check the item feedback in comments below and the seller rating. sometime people add some useful info regarding the quality of item. Also a seller having high order/sales gives better sampling ratio for overall feedback quality.
I use below site for tracking orders once shipped. It will not be DHL/FEDEX style fast, delayed by few days.
Once order is placed in the status tracking tab there is a timer which shows in how many days the item will be auto confirmed as received and payment will be sent to seller. If due to some reason the package is delayed and the timer is coming to end you can extent it till you receive package. Make sure to use this functionality well if you plan to open a dispute with the seller.
On Aliexpress i see some seller going for China Air Mail, some have Singapore Post and some have Swiss Post. What is the difference between these apart from they belonging to different countries. I mean how can they send the stuff from China in a Singapore or Swiss post ?
Many countries postal office have POP(point of presence) in each country where the local post hands over the package which is destined to that country. So for example if once orders from switzerland and the seller has swiss post listing then he would get the item faster as swiss post is fast and excellent, sadly in our case both china and indian postal system are overloaded and not efficiently managed.
Singapore post is usually sent via HK->Singapore->India route. The seller might be probably in Hong Kong. Personally I have found singapore post to be better/faster than china post.