Don't put your aperture at 1.8 just because you can. This will result in slightly out-of-focus shots. Instead, you should set your aperture a couple stops higher. I like to use 2.8 or 3.2.
2. Use back button focusing.
Back button focusing is when you push a certain button on the back of your camera, it will focus instead of when you push the shutter button half-way. Look up how to back button focus on your particular camera.
3. Use a tripod.
If you are taking pictures of food, products, or anything standing still, use a tripod! It will let you use a lower ISO and a slower shutter speed.
4. Think about lighting.
If you are outside, take pictures with the sun behind the person and use a reflector to light up his/face. If you are indoors, have the person face the window.
5. If you have Photoshop, shoot in RAW!
Please, if you have Photoshop or Photoshop Elements, don't shoot JPEG! Shoot RAW! You'll get way better results. I recommend you read this post to learn more about RAW.
6. Examine other's photos.
Now, I don't mean copy. Find a photographer or blogger you love and examine their photos. I love this blogger and this photographer. Ask these questions:
What is her style?
What do I like about her photos?
How can I produce similar photos?
And of course, practice, practice, practice! That is the best thing you can do to get better pictures!
Check out my beginner photography tips here.