Tips for young kids (3 years old) to encourage them to be interested in English?

60 min. is a long time for 3 year olds. The key is to break it up into smaller blocks of activities - by this I mean to physically change your position and even class formation. In general, 3 year olds will enjoy anything that gives them the opportunity to have fun (sing, dance, jump around, etc.). I'm not sure what your program is like and whether you have the room to do this (i.e. are they in tables and chairs, or sitting on the floor in a large room, etc.). In my experience, having a physical type of warm up at the beginning of the class helps to get their interest - my favorite is a "How many jumps?" type of number review. I hold up a number of fingers, and we all jump that many times. There's a lot of spinning around, rolling fists, and sound effects before showing the fingers, but that's the general idea.

When I train my new teachers, I always stress the three S's with the 3-year-olds: Slow, Soft, and Simple. Start out this way to get them on your side. Give lots of individual praise (if a kid says "Hello" immediately give them a high-five. It'll catch on like wildfire!). The content of the class is pretty much irrelevant at the beginning. Whether you teach them colors, numbers, ABCs, animals or whatever, the major thing you want is for them to get interested - not only in English, but in YOU as their teacher. If they like you as a teacher, they'll like whatever you teach them.

Incidentally, here is my lesson plan for a 20-30-minute class. Our classes have no activity books or student books (whatever those are), so adding those on should increase the time length a little.

Greetings - saying hello and good morning with different, silly waves of waving your hands.
Hello Song - you can see a ton on my youtube page (same username).
Warm Up - as written above.
Flashcard Presentation - do lots of tricks when showing the cards (twirling them around, showing it little by little from behind another card, etc.). Concentrate on phonics and SHORT simple sentences ("It's a CAT!"). Go around to several kids and ask them to say the card. Give them a high five after doing so. Present about 4 cards per class.
Game - In a class with 42 kids, I'd assign poses for the cards and do a TPR activity. Something like walking/running in place and then doing the pose when you show the card.
Goodbye song - again, youtube me.

If you can use this lesson plan, you can probably repeat the flashcard presentation and game activities with a new set of cards/poses/game, to make the class longer. As far as the activity book goes, if you have one, you should use it. Or at least do SOME kind of book work - for 3-year-olds just coloring shapes/pictures in a designated color is good enough I think. You can easily make those yourself. Good luck!

I forgot that I changed my YouTube username. My videos are at the username daviddesu now. sorry about the confusion!