Legally, you only need to wear an helmet to ride a motorcycle. In reality you need to be much more safely dressed.
Budget normally decides what you can choose, but if you value your skin then buy the very best you can afford. And cover as much of your body as you can.
Try to wear your most protective kit for every journey you make. If you can't, then take things even more carefully. Though don't forget the very best kit can't ultimately prevent injury.
Leading brands are pricier but you do generally get what you pay for. Helmets can be very expensive, yet as your head is your most important bit to protect then it's a price worth paying. Make sure the fit is snug, but comfortable. Wearing ear plugs reduces noise and the chance of damage to your hearing.
Leather is the best material for protection. Textile clothing is almost as tough and has the bonus of being fully weatherproof. In either case choose clothing with body armor and the best possible fit. Loose kit will not protect properly. Boots and gloves need to be tough and durable. Hand and feet are often the first things to touch down in a crash.
The latest, most fashionable gear can cost ten thousands, but there are ways of saving money without compromising safety. Buying slightly outdated clothing will be much cheaper. Don't however buy cheap quality stuff that will fall apart quickly or be unsafe.
Try to wear something bright and do your best to keep dry and warm.