How do you guys deal with the sun?
Plan for it. Best idea is to avoid the situation if you can. Travel at a different time. Or stop and wait for the sun to go down -- it might not take as long as you think. Sometimes people get a terrible urge to get on, when it would make a lot more sense to stop and watch the world go by for a bit. This will probably all change later in the year, so it might only be a problem for a few weeks.
As has been said there are goodies like strips you can stick on the visor, and peaks. I've used a peak but only on an open face helmet that had no visor. I'd never go back to one of those for everyday wear but it might be worth a try for this particular situation for a few weeks in the year. Personal choice. I've heard horror stories about what unforseen things have been done by things that people have stuck to helmets and visors, and I wouldn't do anything like that.
One trick I use when it's raining is to keep my head moving all the time so that I'm looking through a different part of my visor at any given moment. The brain is remarkably good at sorting the distant signal from the close-up noise and you'll get a better view even through a semi-obscured visor. This also works, but not as well, with a dirty visor and sun.
Otherwise, weeeell, in view of your lack of experience I'm not suggesting you try any of this yourself yet, but...
First off, a visor (in fact
anything between your eyes and the rest of the world) is a bit of a liability when the sun is in your face, especially if it's dirty -- and very often you can't avoid it being dirty. So I will usually lift my visor if the sun is shining on it so strongly that the only things I can see are those that are stuck to the visor. Obviously I will be going more slowly than normal if I'm having difficulty seeing what's there, so the risks from getting something like a rock in my eye are reduced. I can lift the visor in a second and drop it in probably half a second. More to the point I can do it without losing any control of the bike, no matter what else is going on. I don't know if they teach that in the CBT but I think it's an important skill to learn. Now that I think about it I use my right hand to open and close my visor. I think it's odd, as I'm left-handed, but I do.
Secondly, it's not just about speed but about the control you have over the bike. I will want to be in a lower gear than normal, because that gives me more control and I will be driving one handed
so I can use my left (clutch) hand to shade my eyes. I will have more speed flexibility in a lower gear, and at a slow enough speed while shading my eyes with my left hand I can see far enough ahead to be able to change gear using the clutch (so for that fraction of a second I may be dazzled) if I need to and get my hand back to shading my eyes for the next bit of progress along the road. Of course I can easily change up a gear without using the clutch, but I try to avoid it. You might not yet be comfortable handling the bike with only one hand on the bars, and it isn't recommended routine, and I repeat I don't recommend it to you nor to anyone else. It's just what I do in some circumstances when I think it's safer than not doing it. You did ask.
Thirdly, you might be able to use the top of your crash helmet as a sun shield. It depends on the model and the fit. With very strong sun directly in your face, sunglasses and visors built into the helmet aren't a lot of use. My Schuberth helmet has a built-in visor and I find it's only really useful when the sun is high or behind me -- but it is very useful then.
Finally, if the sun is so directly behind the traffic that you really can't see where you're going, even if you can somehow shade your eyes, then you have no choice. Stop. It would be dangerous to proceed. It sounds like you've been in that dangerous area, and you won't live for very long that way.
