One way to find a perfect pair of reading glasses is to go a qualified optometrist who will do a complete examination and then write you out a prescription for the proper lenses. Although more costly than purchasing wholesale reading glasses there are a few advantages.
The advantages have to do with the fact the inexpensive reading glasses will have a ready made prescription that is the same for both eyes. Although they do come in a variety of different shapes and sizes like the more expensive customized models that come with your personalized prescription, most people don't have an identical prescription for both eyes.
So although a little more expensive, it can be advantageous to get prescription reading glasses. Optometrists will work with you individually to find a pair that suits you best--whether you'd prefer and are better suited to full reading glasses that help you with studying documents over a long period of time, or the half readers that are suited to looking up and over what you need to read.
If you do not want to go the expensive route and are fine with inexpensive reading glasses, we have a wide selection available here.
Remember that you should have different glasses for the different things that you need to do with your eyes. In other words, it is not always the best ideas to use reading glasses to look at your computer screen, since reading materials are often held closer than a monitor usually sits. Readers have their proper place but you might need to consider a pair of computer glasses when the need becomes apparent so you can carry on with your laptop or desktop.