I'm far from a photography expert; I've been using my Canon 500d camera for just over two years now and for most of that time had been using auto settings until I recently bit the bullet and educated myself on the manual settings. Assuming that buying a fancy camera will instantly make your photos look of professional standard is a huge mistake - so many factors go into what makes a great photo, including lighting, backgrounds, getting to know your camera and also using editing software for the finished picture. I have become a complete perfectionist when it comes to taking photos of beauty products and bad lighting or unfocused images really bother me. I've made a little list of what to watch out when taking pictures, it's kind of like a little mental check list that I run through when shooting images.
AVOID CLUTTERED BACKGROUNDS - For most of my photos I use a white background which for close up shots is a piece of A4 paper laid on my window sill and for larger products is a white pillow case laid in front of a white wall. You can always have some products in the background of your image but be sure that you blur the background so that the focus is on the product that you are reviewing. Personally I much prefer the clean look of a plain white background and find it makes products stand out much more. If you have pretty bedsheets or fabrics those look great too and can give your pictures more of a unique twist.
MAKE SURE THE LIGHTING IS JUST RIGHT - Natural lighting is always a must for my photos, I find that it always brings out the best colours and looks the prettiest. The windowsill is my favourite place for photographing as it's the place that is flooded with most light in the house. On days that the weather has been horrendous and cloudy outside it makes such an impact on the quality of my photos so it's always worth keeping in mind to take advantage of sunny days.
STEP AWAY FROM THE FLASH - Obviously it's completely up to you as to how you take your photos but I really dislike images of beauty products with the use of flash. If you take time to use natural lighting to your benefit you should pretty much never need to use the flash setting apart from on the rare occasion to show the glitter in a product etc. It rarely shows the true colours of a product too and often gives flash spots to packaging.
WITHOUT FLASH AND GOOD LIGHTING
TAKE A LARGE BATCH OF PHOTOS - You can have everything set up perfectly but it certainly doesn't mean that you will get that perfect shot straight away. Try different angles and zooming in and out to get the best photo, I find this tip absolutely key when it comes to taking photos of nail polish swatches as tilting my hand ever so slightly can mean that glitter shows up so much better if it catches the light. I can take anywhere from 4-50 photos for just one post and from there choose the best ones from the bunch to make the cut.
OUT OF FOCUS
I'm still finding my way when it comes to photography for my blog, I pick up new tips all of the time and find out new tricks through trial and error, so please leave some of your tips in the comments.