Honestly, I'm not good with presents....I usually try to get jewelry, clothes, mushy crap, etc. If we're out at the mall, I try to pay attention to what she likes and what she doesn't.
First, congrats on the engagement for both of you. I hope you have the best time together for the rest of your lives.
As for the gifts, this is where I have some talent. I was always good with gifts. The key isn't watching, it's listening. For example my exgirlfriend loved to go out at night, always talked about how nice the night was, loved looking at stars, etc. One of the things I got her for her birthday was an indoor planeterium. The kind that projects the main constellations onto your ceiling. She loved it.
Another girl I know, not a girlfriend, whose birthday passed not too long ago got a certain scent of incense and a few of those scented oil perfume type thingies. Different types of musk scents. She mentioned in passing sometime last year that they had stopped making her favorite incense scent, and how much she loved those oils. She got those and a few other goofy little things. I like giving presents to people. It's fun.
But the key is listening and remembering. And then seeing if you can get a relevant gift that kind of mixes yourself into it a bit too. Me being a geek, reading astronomy magazines and such, the planeterium thing was a reminder of me but something
for her, that sort of thing. I also got her a beach themed journal because she wrote a lot at the beach but couldn't go there as often as she liked.
When you get a girl something related to something she said in passing a year or two ago, and she makes the connection, you'll trust me when I say it makes an impression. So do what I did, train yourself to key in on those little things they mention. It pays off in the end, you get to make them real happy with a cute present here and there.