Don't waste your money on these, unless you feel like it.
Motorcycles are so customizable. Everyone wants to tweak their rides to their own personal preferences. Without experience, though, new riders may tend to make some mods that don't do anything, cost too much, or are simply unsafe. Yammie Noob lists seven of these... well, actually six, since one item on his list he actually recommends as a good idea.
1. Bubble Windscreen
These look cool, and they do help guide the air around you when you're in a full tuck blasting down the front straightaway of your favorite track. For the street, though, you aren't (or at least shouldn't be) going fast enough for this to make any difference in your bike's performance whatsoever. Believe me, your boss is not going to care that you got to the office three seconds faster than yesterday. Unless you really like the look and want one for that reason alone, save your money for something that will transform your bike's handling.
2. Cheap Tires
Take the money you saved on the bubble windscreen and spend it on your tires. All of your bike's performance is relying on those two tiny contact patches underneath you. You want those contact patches to be of the highest quality possible, and since you can't control the road, you should buy the best tires you can afford. We've written complete guides to choosing tires in the past. Read those, then pick the best tire for your type of bike and your type of riding that fits your budget.
3. Tank Grips (But These Are Actually Good)
Even though this is supposed to be a list of what not to do, Yammie turns around and highly recommends adding tank grips to any bike you ride. Kate agrees and highly recommends them herself. If you can grip the gas tank with your knees, that leaves the rest of your body free to control the bike. You can't operate handlebar controls as well when you're simultaneously grabbing on for dear life. In all my years of riding, I have never learned to grip the tank with my knees. Maybe I should pick up some tank grips as a reminder and teach myself this skill.
4. Aftermarket Handlebar Grips
Here's a point on which Yammie and I disagree. He says not to bother upgrading your grips, because even the shiniest, most expensive grips are not going to help your throttle control skills. He's right that they won't help your skills, but I disagree that grips are a waste of money. My Honda PC800's handlebars are infamously too small for comfort, a mere 7/8 inch diameter. The community's common modification, which I've done to my bike, is to slide foam Grip Puppies over the stock grips. Not only are they soft and cushy, they effectively enlarge the grip diameter, making them much easier to hold onto, improving control. Yammie is correct that without having the proper throttle control skills in the first place, these won't help, but I would say that grips can help add control as well. The best scenario is having both the grips and the skills.
5. Removing Your Mirrors
This one, however, is just plain dumb unless you're actively on the track. Most track days require you to remove your mirrors, or at least tape over them so you can't use them, so that you focus on what's in front of you, not behind you. It's also one less thing to break if you drop the bike, and one less source of potentially tire slashing glass as well.
On the street, though, everybody is trying to kill you. They come from all directions, including from behind. You need to be able to see behind you to know if someone is about to mow you down so you can take corrective action in time. Keep the mirrors. Use a different style, like bar-ends, if you like. Don't get rid of them, though.
6. Aftermarket Exhaust
Some bikes don't even go for their first ride without an aftermarket exhaust being installed on them, because loud pipes save lives (not really). This affects your engine's fuel/air ratio, though. Many modern bikes are already tuned by the factory to run lean to pass emissions testing. Opening up the exhaust will make them run even leaner, meaning there will be too much air and not enough fuel to make the engine run well. It'll need a retuning if it's fuel injected, or if it's carbureted it's time to open it up and drill or replace some jets. Do you really want to go through that kind of trouble for your first bike? The truth is that you'll end up going much faster by improving your riding skills than by any small gain a couple extra horsepower will give you.
I can understand wanting a nicer sound out of the bike, though. One time I almost dropped my wife's Suzuki Savage when it stalled during a downshift just before I entered a corner. The engine is so quiet when it's running that I didn't hear when it stopped, causing me to skid sideways under engine braking when I turned in. If that bike wasn't so small and light that I was able to muscle it back under control, I would've crashed it for sure. So an aftermarket slip-on exhaust is fine for giving your bike a little more rumble. There might have been a drilled-out version of a stock Savage exhaust on the parts bike, at least at the time...
7. Only Using a Tinted Visor
Tinted visors are great—in bright sunlight. No matter how much Corey Hart may preach the virtues of tinted lenses in dark conditions, however, they're not cool. To ride a motorcycle, you need to be able to see. Swap that tinted visor out for a clear one. Make sure you can do it without tools, because if it's a pain to swap them, you simply won't bother. I positively love the tinted sun visor that extends and retracts in and out of my Nolan helmet, an increasingly common feature in helmets these days. It's even better for people like me who wear glasses and don't have to pull over to swap lenses from clear to dark.
Yammie Noob makes one more point throughout this video that I think is important to mention. Your first bike, in most cases, isn't your forever bike. You're not going to keep that Ninja 300 or Boulevard S40 forever. Any money you spend on modifying your first bike will probably be lost when you eventually sell it and have to make the same mods to your next bike. Sure, these bikes have deficiencies and imperfections that you can improve on. Ride it in stock form, though, to learn exactly what you like and don't like from your first bike. Then, when you get a bike that you really will keep a while, you can modify it intelligently to suit the riding tastes you developed from your first bike.