If your daughter is fond of skirts and dresses, sewing her clothes should be very simple. I am not much of a sewer, but I can bang out a pleated wrap dress in a couple of hours from scratch. Sadly, I dont really wear dresses. Trousers are terra incognita for me.
Yeah, I totally make my own clothes. I make everything except shoes (and a couple of times, have even made those). To learn sewing tips and techniques, I suggest you visit sewing.patternreview.com, burdastyle.com, and just start going to youtube.com and watching videos. If you live where you can go to a public library, there should be available books.
Now about your daughter being an atypical size, if you give us more details, I can try to give some design help. For most people you're going to learn some fit techniques by which you can alter standard patterns for each person. For some people (thinking achondroplasia or other types of significant difference), you may need to learn pattern drafting skills.
I'm late to this party, but if you don't sew at all yet, I would recommend finding a shop near you that has some basic classes. Books are very helpful once you have the basics down, but they can't teach you how to handle a sewing machine and fabric, how to place pins or hold the threads, or any of those little details. A couple classes should be enough to get you started to a point where you can navigate a pattern on your own. If your daughter likes loose, desert-style clothes, that's good - not much shaping involved! Here's a really nice example:
The same authors did a sequel titled Son of the illustrated etc
No patterns necessary. They talk about hand-sewing as well as machine sewing.
When I was growing up, sewing your own was the cheapest way to go. These days, if you consider only the cash outlay, W****t is cheaper than making your own. But most of the clothes are crap, not meant to last.
You can teach yourself to hand sew pretty easily - all you need to know to start is a back stitch and a running stitch, I'd be astounded if there are no online illustrations. And basic sewing machine isn't hard to learn either. The caveat is that there are lots of crappy sewing machines out there that will always be slightly annoying to use, and you'll think it's you, when it's not.
Basic sewing classes are still taught through community education programs, so look around. If you can afford $300-$500 for a sewing machine, buy it at a sewing machine dealer that offers classes. At that price, I think a Bernina would be your best bet, either a new or reconditioned machine.
Do you have a friend that sews?
Here's a thought - be adventurous. Go to a thrift store, buy some t-shirt style tops in good fabric that are too large for the ultimate wearer - then cut the pieces apart along the seam lines, study how they're put together, then try altering them to fit. Unsuccessful attempts can always be used for paint clothes! Do that a few times, you'll learn a lot.
Start simple and don't be afraid of making mistakes. If you find a pattern that almost fits, make notes on what needs to be different, get a role of sturdy paper and using the pattern and your notes, and cut out your own pattern. It's not hard, it's just a matter of not being intimidated.