Garage sales are my best friend! Like consignment, but usually cheaper :) The thing I've found with baby clothes is they can VARY like crazy. My 2 year old still wears some 12 months clothes and other 3T clothes, as well as 18 months, 24months/2T. I would stick with mostly 2T for next summer, but have some 3T's on hand, just in case.
Hope this helps :)

I also shop ahead for my daughter. One of our upstairs rooms is devoted to tubs of clothes for her to grow into! (and tubs of clothes and toys she has grown out of, waiting for the next one!).

When she was smaller and growing faster, I would usually buy three sizes up for the next season -- so summer 2009 I bought for summer 2010 and she was in 6 month clothes so I bought 18 month clothes, which was right on. Now she is growing slower so I usually buy one size up for the next season. This summer she is in mostly 2T so I bought 3T/some 4T for next summer.

I don't usually buy her shoes ahead of time, her feet grow much less predictably than the rest of her. I usually buy her shoes at Target and there are certain styles I like, so I might buy the next size up or something if they were on clearance since I know they fit her well and that way I will have them in the future. I HATE IT when the shoes we like go out of production!! She is a bit fussy about her feet, will not wear shoes without socks, so finding shoes that work for her can be a bit hard. I'm taking her tomorrow to a "real" shoe store to get her feet measured and buy her a pair of good sneakers for fall/winter. Hoping to get a deal at the back to school sales.

I will shop clearance sales -- like this time of year (and actually earlier, more like July), is a good time to do Gymboree/Children's Place/Gap/Carter's/Oshkosh for summer stuff for next year. I made the rounds of those clearance sales. Then in February I will do winter clearance, May I will do spring clearance, and November I will do fall clearance.

I also shop consignment stores/thrift stores. Thrift stores in particular can be awesome. I try to go to the ones in the "nicer" towns in my area, because they tend to have more of the name brand clothing. When I get something like jeans from Gymboree (which run up to $30) for $5 at a thrift store... it's amazing. Consignment can be good but sometimes overpriced. I shop at a children's used clothing store called The Children's Orchard (they are a chain, you could see if they have one near you). For stuff like jeans, Halloween costumes, winter coats, etc., they are a great deal. And sometimes you find something brand new with tags that is a fraction of what it would have cost new. I am careful what I buy there now, though, because sometimes the clothes are not in as good a shape as they should be, even used, to pay the prices. They do this super-cool thing, though, called Stuff-a-Bag, where they put out bins and bins of clothes they can't sell for whatever reason and you get as many grocery bags as you can stuff for $5 a bag. It is a big deal, I show up at least an hour before it starts to be in the front of the crowd. It's first-come, first-served. Last time I was there, there were over 400 people. Some of the clothes are junk and it's all seasons mixed together but I have gotten a lot of nice clothes that way.

And then I do sometimes get clothes for free. I have a friend whose daughter is 16 months older than mine, so she gives me all her daughter's hand-me-downs, which has been nice. I pass on anything that doesn't work for Natalie to some friends of ours who don't have a lot of money. I have also done something called Freecycle, which is nationwide. People post things they don't want anymore and if you come and pick them up, they are yours. I've gotten clothes that way before. I don't do it much anymore because while sometimes I have gotten amazing things (when my daughter was a newborn I got 3 garbage bags full of baby girl clothes, freshly laundered, no stains, some with tags still on) I more often get junk or gross things (8 garbage bags of dirty, stained, torn clothes and shoes, filthy socks, and food and bugs -- those went to the dump). Our library also sometimes does a clothing swap. You bring a bag of clothes you don't want anymore and can pick out clothes to take instead. The idea is to bring more than you take and the leftovers get donated to Goodwill.

I usually try to stick with name brands because they fit so much better, so it's really important I shop frugally. I can't even imagine paying full price for some of these companies, Gymboree for example!

I actually try to keep my season shopping for the season right before the one I'm shopping for. So right now it's summer, so I shop for fall and a little bit for winter. This way I don't over size or under size lol. For instance, I hit a good sale at Children's Place and bought 4 pairs of jeans....size 3T because all they had was a 2 otherwise and I didn't think that would fit. Well, a 2 would of done....she's not that tall lol. So now I have to hope if she doesn't fit them this year that she will next year.

I also like to shop online. kidsteals.com or babysteals.com are FANTASTIC! And the shipping isn't that bad, and I live in Canada and they ship out of the States!

I am part of a group too that's local that does 'clothes swap'. You bring all your old clothes to a meet and you swap out what you have for what you need. Alot of the time I just pass my clothes on or sell them and the money we make goes into her college fund. But sometimes I hit those meetings.

Also, I love value village lol. They have thier 50% off days and it's a great time to get clothes for cheap. She grows so fast that I hate buying new unless it's on sale.

With twins I have to be really frugal when shopping for clothes. I do like to get the cheap stuff from Wal Mart if its cute (some of the fashions that go through there don't make a lot of sence to me) but mostly I stick with D.I. (Deseret Industries) and Kid to Kid both of which sell used items. I find a lot of cute stuff and don't have to pay out the nose for it.

Also, I have no trouble buying oversized. Last year I bought 3T PJs with the footed feet because at that time my kids were growing so fast I was sure they'd barely last til the end of last winter. Well they slowed down in the growing dept and just yesterday I put one of my daughters into a set from last winter and it still fit... a bit snuggly mind you but she didn't care. it was still comfortable and not too tight yet. Sometimes having baggy clothes isn't that bad... especially at this age. No one cares and it helps the money go further cause you get more use then you might originally have had.

I too love getting a great deal. I love to go to Garage sales I usually get our local paper and go to any that advertise clothes in DD size. Another idea is to check and see if your area has any Mom to Mom sales. Last year I made it to a really large one and bought an entire wardrobe in one day for less than $50. I havnt had the time to go to garage sales this year so will try to make a Mom to Mom sale and also the consignment shops.

Craigslist all the way. Plus we have an awesome consignment shop here. This lets me buy current sizing instead of guessing what they will be in when.

I wish I were like you. I never buy anything ahead and I can never find anything on sale that I like. I buy my son from Ralph Lauren/Polo,Janie and Jack,Burberry,and J Crew crew cuts and mini boden that's it. I won't even let people buy him presents that are clothes because I am so picky. When he out grows his clothes I give them away to a very good friend. I wish I wasn't like this---I totally have a shopping addiction!

My daughter is 16 months also and everything I have for this winter is 18 or 24 months size and everything for next spring/summer is 2T. There is a big difference beteween 24 months and 2T. My daughter is a little chunky and is 9oth percentile for her height and weight so i am hoping I did the right thing with purchasing 24 month sizes for fall. Hemming is a good idea for jeans and pants! I have a mother in law who loves to sew so I might be keeping her busy this winter lol!

Ebay is another good idea. You can get designer clothing for babies on there for a great price, sometimes new and never worn. There are mom's who overshop and so the kids don't get to wear everything before they outgrow it. That way you can shop for the season and know what size your DD is. I've got a 19 month old daughter who I have bought winter clothing for in size 24 months/2T but I'm afraid to buy for next summer because I'm not sure what size she'll wear then. It sounds like your daughter might actually fit into the 24m/2T stuff you bought fpr winter if the 18 M size clothing is getting tight now. I do shop clearance as well as consignment stores too. We have Kid 2 Kid here as well as Other Mother's and they're both great! I share your baby clothes shopping passion.