The absolute first thing I noticed when I got the idea to take a motorcycle license was that to be able to ride you need all kinds of gear. It’s not like driving a car where all you need is, well, nothing specific really. To ride a bike here in Sweden you are legally required to wear a helmet, and for my insurance to be valid I also need to wear proper motorcycle clothing, gloves, boots and a back protector. Good underwear is also important unless you want to be very sweaty.
In all honesty, if you do get into an accident you will be more happy than sorry for making the trouble to wear proper equipment. Though, what you might not realize beforehand is how much these things actually cost! At least I was not very prepared for it. I ended up buying the first cheap clothes I bumped into, but I made sure to get a good helmet and good boots, all in all it landed on about €1000. That is actually quite cheap for an complete new kit as you can easily find just a jacket that costs half of that.
If you are low on cash an alternative is to buy used stuff. When I was shopping for headgear I got told that a new helmet eventually shapes itself after your head and that the structural integrity can be compromised by simply dropping it on the ground once. This means that if you get a second hand helmet it might never fit your head and you are taking some chances as you don’t know what has happened to it previously!
Another thing I was told later was to make sure that I got a helmet which you fasten with a strap and D-rings. It is more likely to still be on your head after a crash than if you get a helmet with a quick release buckle.
I previously mentioned that my insurance requires me to wear protective gear, it also requires me to lock my bike with two certified locks. I got myself a chain for the rear wheel and a padlock to put in my front disk breaks. They are a bit of a hassle but when I park the bike in the garage or outdoors overnight I make sure to get both on.
This automatically leads me into the last thing to get if you are going to practice privately, the bike itself. I bought a very old and quite heavy veteran motorcycle, but it was also fairly cheap and it actually runs pretty well, as soon as it has warmed up that is. For training this might not be a necessary purchase for you but here in Sweden you have to pass a practical risk course before you can even do the theory test, and as I could not easily find a practice bike to borrow I bought one.