RINGSLING = A ring sling (RS) is a long piece of fabric with a set of metal rings sewn into one end. The sling then wraps around you, from shoulder to midsection, with the other end threaded through the rings to create an adjustable lock of sorts. The fabric is then folded in half to create a sort of  hammock for the baby to rest in against either your chest, back, or on your hip. (source)

so it has a pair or rings, it comes in different fabrics, in various of length, with different in shoulder styles and bla bla..
 
if a friend ask me, i will explain the basic in choosing an RS (so this is solely base on my limited experiences & knowledge, SO feel free to add on thanks  )
 
rings: can be either small, medium or large. rule of thumb, large rings for thicker fabric and small rings for thinner fabric so easier to go through the small rings.
nylon vs aluminium. Nylon rings have slippery issue but with a grippy fabric, this wont be an issue, some mamas like nylon rings more than aluminium...
 
fabrics:
linen, cotton, silk or wrap fabric (usually woven fabric).
Linen is airy, new one maybe stiff, but very soft once broken in.
Cotton is airy too but slightly thicker than linen, but soften (broken in) easily.
Silk is exclusive and has luxury-look to it, may need extra care (but i dont know much about silk, sorry).
And lastly wraps fabric (we call it WCRS = wrap conversion ringsling) -- depending on the wraps - thick, think, supportive etc.. but for me, wcrs is the best!
 
length:
u should pick depending on your body size and your preference of the tail (long or short tail). i love tail down to my knees, or at mid-thigh. Some would prefer longer tail so easy to cover when BF. And craddle carry requires longer sling as the baby position will take up more fabrics to make out a pouch. So, maybe you could ask the maker if u are buying one for the first time, they know their customers best  ;D
OR ask around, other mamas who are about the same height/weight with you, what is their preferred length etc..
 
shoulder style:
gathered, pleat, hotdog, SBPed, jumpsac's, psling's etc - dont worry about it, the worse thing u can do is, try them all and see which style u prefer most  :P
if u ask me, i preferred padded -- less shoulder strain = 'empuk', need not much adjustment -- so i preferred jumpsac, psling & hotdog-style  ;D
what i dont like about other style?
pleat -- i still can accept this cos it is somewhat slightly 'padded'
SBP'ed -- it's like pleated shoulder, just the name and the way the pleats are 'arranged'
gathered -- dont like the bunch of fabric on my shoulder. I need to adjust the fabric to get the best position, so, too lazy for it, plus it restricts my arm
 
so newbies, i always say go for jumpsac or pleat, but it's not wrong to try others
 
hmmm what else??
 
brands? -- nope cant give you one answer. There are many many many brands with different shoulder styles, different fabric used, different patterns etc.. so u gotta know the difference, and pick the one that u like most
 
price? -- depending on brands and fabrics... local RS are wayyy affordable than oversea-made. But heyyy our local brands are as good or even better laa... i still    JS!!
Used ones are wayy cheaper, but dont expect the price to be halfed of the retail's cos babywearing gadgets have their secondhand values.. i dont mind used slings cos they are usually broken-in and SOFT 
 
okay, what else do u need to know about RS??
 
ask away... and do add infos in this thread ok... 
 
 

shoulder style:
hybrid: combination of 2 types. for eg: Comfy Joey and apootaern. both have gathered with some pleat.

on SBP - it is pleated la kan (not 'like' pleated). it is one example of pleated. SBP = sleeping baby production is the brand name. named after the maker company/business.

there are other kind of pleated shoulder..er..eesti (?) maybe..

3) Psling:
- accordian shoulder..
- the fabric is sewn in accordian style and Psling comes with right and right shoulder
- no need to adjust/ spreading the fabric on the shoulder
- it's like having a padded shoulder


close-up to show the accordion:


this is how it looks on the shoulder:


4) Pleated shoulder:
- also known as SBPed shoulder (because this is originally the idea of Jan Andrea, the owner of Sleeping Baby Production-SBP)
- fabric is nicely sewn in pleated and looks neater on the shoulder (this is why like about pleated, looks nice n neat on our shoulder
- no need to adjust/ spreading the fabric on the shoulder
- i like this style, but when my baby is getting bigger, i'm not into it, it digs my shoulder 


this is how it looks on the shoulder:


5) Hybrid shoulder:
- this can be found in Comfy Joey RS
- can be used as gathered or pleated shoulder...means u can spread the shoulder, or can be worn narrowly by scrunching up the fabric on the shoulder

*sorry for the crappy pic, if u have better pic, pls post it here 

this is how it looks on the shoulder:


6) Hotdog shoulder:
- i haven't try or see this kind of shoulder IRL, but from what I read, the fabric is folded lengthwise towards the center of the sling, before being sewn to the rings (correct me if i'm wrong hehe)

*no pic from me, but do update if u have the pic of this style, i think leo's ex wcrs zara has this shoulder try...will re-confirm with her later

hi.. im newby for RS.. just want to get one soon, but still think which suit best for me.., i have look for jumpsac.. so far i like bcoz it has padded on shoulder.., but i still looking for the best, what is ur suggest for best RS for a newby.. tia. 

what do u think about plastic ring sling? i read somewhere bfr that plastic rings tend to break after a few years of use.certain rs use plastic ring but im not too sure about the safety of the baby. any comments?

Jumpsac is lightly padded. Maya RS also lightly padded (i think). any feedback from those yg pernah tried both?

hi.. im newby for RS.. just want to get one soon, but still think which suit best for me.., i have look for jumpsac.. so far i like bcoz it has padded on shoulder.., but i still looking for the best, what is ur suggest for best RS for a newby.. tia. 

hi norly, do introduce yourself in Introduction board ya
if u're newbie, i would suggest u go for jumpsac, the easiest one to get because it's available in our local market..
padded shoulder is beginner friendly, it's easy to thread/adjust cos most jumpsac RS comes with large ring sling..

how old is you baby, btw?

samalah tu pah..

I have one ring sling with nylon rings... sooooooooo tak suka..   
sibek hadiah menang contest.

norly,
u can find Jumpsac online store here: Jumpsac...so many info about this RS can be found there..

or u can go to our FSOT forum here: FSOT and look for a 2nd hand Jumpsac or other types/brands of RS..

*farrahar is selling her Jumpsac RS at great bargain!

HTH!