I have recently purchased a new acoustic guitar, and the stock strings aren't too good. Problem is, I have never changed the strings on any of my guitars because my electric was used and new strings(don't know brand or gauge) were installed on it and the stocks on my bass were very good.

How do I go about deciding what type of strings to get?

if you like whats on there already bring the guitar to the store and ask the employees for the same

or just get a set you think is good, medium is a good place to start, and see how you like 'em and go from there
Acoustic guitar strings are very simple to replace. Check the acoustic guitar set up guide thread in the stickies at the top of this form. Should teach you everything you need to know to change your strings.

^Buy light gauge strings, since light is pretty much the standard gauge on most acoustic guitars anyways.
ya, sorry, light is probably better to start on, but if you've been playing for a while you might prefer medium, all depends on you
Not quite that simple... Many acoustic guitars are manufactured to respond best to a particular gauge of string. Many larger "dreadnaught" and "jumbo" sized instruments will respond better to mediums.
Smaller instruments may be set up to handle lights, and installing medium-gauge strings may damage the instrument.
In addition, going from say, lights to mediums may require that the nut slots be adjusted or the truss rod be adjusted to compensate for the extra tension.
Take the guitar to the shop; they will put a micrometer on the strings and tell you what gauge strings are on the guitar.
Then you can decide on a brand and type. There are dozens....
truss rod adjustment yes but nut slot widening for mediums from lights, probably not, yes in theory, but in practice mediums will most likely fit on a guitar built with lights no problem
Thank you. I might just go to the store, try a guitar with strings I am used to and ask the sales person what gauge those are.