First of all, you can buy a new factory-made charger that’s made specifically for your device. If you’re the extremely cautious type you can rest assured that this is the safest option possible because your new charger will perfectly match your device. Unfortunately, it’s also the most expensive option, and in fact quite unnecessary.
One of the best options if your phone is older or isn’t that expensive a model is to simply use an old (but working) charger that you already own. Most of us have a drawer full of old chargers sitting around, just taking up space. Chances are one or more of those will work just fine with your phone, especially if you tend to remain with the same brand when you upgrade.
Just make sure the connector fits without forcing it, the voltage matches the requirements of your device, and the amperage supplied by the charger matches or exceed what the phone requires. You should be able to find the charger’s voltage/amperage on the charger’s label. If not, don’t use it!
Another great option is to buy a high quality third-party phone charger. If you decide to go this route, be sure to go with a well-known brand in a model that has lots of great user reviews. There’s no reason to put your expensive phone at risk when it’s so easy to avoid it. A great way to do that is to look up the model(s) you’re interested in on Amazon and read the reviews that other users have left for it.
And now a final note: Except for Apple products, most new mobile phones come quipped with standard Micro-USB connectors which makes it very easy to share a single charger among several different devices. Just be sure to take into consideration the amperage requirement of your phone(s) as mentioned above.