Hi! First, good luck on your craft fair! Your stuff is really cute! Your first show will be a real trial run to see how you want to set your booth up, what sells, what doesn't, etc. Do not get discouraged or disappointed if things do not go as you hope or plan; there WILL be surprises along the way! It is a learning experience.
Okay, a few questions:
Indoor or outdoor?
Are you renting a single table, or a space (like a 10x10ft booth space)?
If you have a booth space, are you bringing your own table and chairs? What other display items do you have?
I do a lot of indoor conventions where I am only allowed ONE table, whatever size the convention gives me (usually 6ft long by 2-3 ft wide, which really isn't much.) I've learned to build vertically. I have a lot of wire cubes that I use to make pillars on my table so I can hang stuff off of them. If you have multiple tables you will have better opportunity to spread out.
Whether you will be too cluttered, depends on how much space you have and how much inventory you have. There are ways to have a lot of stuff without it being cluttered, you just have to be inventive about your setup. Definitely walk around the show, and any show that you go to, whether you're a vendor or a customer, and see how other people set their booths up. You can get a lot of good ideas by observing others.
As far as engaging the customer, be friendly and polite. If someone is eyeing your booth from a little ways away, say hello to them. Even if people are just walking past my booth, sometimes I say hi in passing. Definitely if someone comes up to your booth and starts checking your stuff out, absolutely greet them, ask them how their day is, if they're having fun at the fair, etc. Offer to answer any questions they have. If they are looking at a particular section (like the baby clothes) start talking about them, saying what they're made out of, how they fit, why they're great, etc. Sell yourself. One of the most annoying things that I find about sellers are the ones who sit in their booth and watch you while you look around without saying a word to you. Perhaps this is personal preference but I always do well when I chat people up.
Um, hm. There's a lot I can say. A few general tips:
Make sure you have a lockbox and starting change. You don't want to be messing with your wallet for change. I always bring $100 with me in starting change; $50 in $1s, $40 in $5s and one $10. I do a lot of small items that are under $10. If you have slightly more expensive items, you might want more $5s and less $1s. Of course, you don't have to start with $100, when I first started vending I think I started with about $30. Make sure you keep your lockbox with you all the time, or with someone you trust. If you have to go to the bathroom and leave your booth unattended, ask your neighbor if they could just keep an eye on the booth for a moment, but bring your lockbox with you to the bathroom.
I hope you have someone to bring with you to help, it makes things much easier!
I like to pack snacks. If you are doing an outdoor craft fair, chances are there will be food there, but if you get busy you may not get a chance to go looking for food. At the very least bring some water, there's nothing worse than getting dehydrated.
Write down (or somehow keep track of) everything that sells, and for how much. At the end of the day, determine what sold the best and what sold the worst. Don't necessarily dismiss the items that didn't sell well, though, especially since this is your first show. I keep a spreadsheet with all my sales in it so I can see what's always popular, what's popular at certain venues, and what just doesn't sell well in general. After a few shows, you'll have a better idea of what to make more of. Oh, and the reason I said to keep track of how much stuff sells for is just because I tend to give discounts to people who buy a lot of things. Obviously you don't have to, but I like to and it encourages repeat business. I had a lady once come to my booth and buy $300 worth of stuff. I gave it to her for $280. The next month she came back to the same show and bought another $100 worth of stuff.
I could go on and on but the best way to learn is to jump in feet first. Get there early so you have plenty of time to set up and fix/change things that need to be fixed or changed (like your booth setup or whatever.) Do not get too stressed. Remember, this is supposed to be fun! I love vending, I hope you have a great time and do well.