Motorcycle boots are extremely important, assuming that you want to protect your feet and ankles. If you don't want to invest in a pair of boots designed specifically for motorcycle riding, you probably can get by with a pair of stiff, supportive and protective general-purpose boots, such as work boots. But that's not an ideal solution, and we'll explain why.
First: Motorcycle riding is so dangerous that the expense of protective gear should be factored into the cost of entry. Don't spend your wad on a bike and then cry poor when it comes to suiting up. Good work boots will protect against most motorcycle hazards, but they'll wear out fast and won't provide much stability in a crash. If you need to wear work boots until you find a good pair of motorcycle boots, focus on trading up sooner rather than later. Don't even think about sneakers, sandals or anything else that doesn't cover the entire foot and ankle. Just don't. Every time you stop, you need to support your weight as well as the weight of your bike. A flip-flop isn't going to cut it.
Motorcycle boots should fit well and be comfortable. If your feet aren't comfortable, it'll contribute to distraction and fatigue while riding. Motorcycle boots also need to provide protection from the bike's exhaust pipes, extreme cold and other weather conditions, and road debris. The soles should be flat (rather than heeled), able to stand up to frequent road impact, be resistant to oil and other chemicals, and maintain good traction with the road, the bike's pegs and the gear shifter. The ultimate test comes in a crash. A pair of boots should protect against foot and ankle injury in most accidents.
To find high-quality motorcycle boots, first consider your specific needs. If your riding needs are specialized, such as motocross, off-roading or racing, there are boots specific to those purposes and many others. For most casual riders or beginners, though, general motorcycle boots are fine. They will typically offer protective lining in Kevlar, steel or another material as well as enough structural strength to prevent your feet and ankles from being crushed, wrenched or twisted in a crash. The last important consideration is the fit: Motorcycle boots should be snug but not tight, worn with socks that will keep you comfortable.