I'm planning on stretching my nostrils, and I was hoping to begin soon and head to a 12g from the 14g I'm at. They're been pierced for 3 months. Any tips on how much longer I should wait if I should at all? And any tips on how I might upsize? Tape, tapers, just letting it stretch itself to the next size naturally, etc. Thanks!

 At least 6-8 months before stretching a new piercing. Get high quality IS tapers if you end up tapering, but the more self stretching you can manage the better. Taping seems really fiddly there, but I have never stretched my nostrils so maybe Eric or KaitlinN will come around with advice for you, they have both stretched theirs. 

 They won't stretch themselves to the next size unless you wear solid steel plugs for a year or two nonstop. I waited 6 months before stretching to 12g from 14g, and it still hurt like hell. In this area, you're always going to experience some stinging and eyewatering, no matter how long you wait. You definitely need to wait a long time between stretches, like, I'm talking 4 or 5 months, and then stretch by halfsizes only. I've always tapered mine, because they close up so quickly. I don't have time to wrap the plug in some tape because it won't go back in if I do. I've been stretching mine for a year and a half and I'm just at 6g. Despite being at 6g for 3.5 months now, I can't leave them out for morethan about 10 seconds or it stings to put back in. :/

I had my nostrils stretched for awhile before letting them completely go. time is your friend when stretching this area. I always just used a taper

Alright awesome. Any suggestions as to what I should be using for tapers? Probably industrial strength tapers or something like that?

You want a nice, long, and gradual taper.

 IS tapers are great. I would avoid the economy steel and acrylic tapers for this.

 You pretty much NEED the IS tapers. Stretching them is difficult to the point where it hurts to jsut get 1/8" of an IS taper in. It takes me about 10 minutes to stretch each nostril when I taper them, if not longer. Your eyes will explode with pain if you try to stretch the thing all at once.

Haha alright. Thanks for the heads up!

i did half sizes and trapers for mine

to be fair, I only had mine at 14g tops. but like Eric said, it hurts like hell!