I mostly get around on bicycle. I'm a bicyclist in the sense that it is my primary means of transportation, but I'm definitely not an enthusiastic bicyclist in the sense that I want to spend time on my bicycle. I want my bicycle to be as care-free and as cheap as possible. Yes, these two can easily be at odds, but they can also go together. For instance, some of the low-weight, high-speed bicycle gear is definitely not care-free.
Now when it comes to the pedals, there are a couple of things I've learned from 20 years of maintenance.
Which ones to buy
First, there are two kinds of cheap pedals. There are the ultra cheap ones that claim to be completely sealed, hence needing no maintenance.
This turns out to be a lie. The sealing means that it is really difficult to maintain them, but it does not stop water from leaking in and ruining the oiling of the ball bearings.
It took me some years to understand how, but I think it's simply a basic physical property of the metal that when you apply pressure to it, it will flex just a tiny amount, and that tiny amount is enough to let water in when you're bicycling in wet weather.
So eventually, the drive train starts creaking, and it turns out it's the pedals, and then it is really difficult to get any kind of greasing into them, so you end up having to buy new ones. I thought for some years that this was okay, due to the low price. But for me it's really just cumbersome (buying stuff takes time) and distasteful to have to discard a big lump of metal each year.
And it turns out there is another kind of cheap, just slightly less cheap, pedal which allows you to remove the end cap that faces outwards so you can easily get to the ball bearings. That end cap is not under pressure, so I don't think it makes the pedal more leaky, but it does make it trivial to get the ball bearings re-oiled. So these pedals last a lot longer.
One thing I did learn is that pedals is a wear part. In retrospect that should not be surprising, after all it's the main interface for transferring power from your body to the bicycle. So you need to be able to take pedals off, even if it's just for oiling.
Unfortunately, pedals can get stuck pretty hard on the pedal arms. It probably does not help that many pedal arms are made of aluminium while the cheap pedals are steel, so they tend to grow fond of each other.
So, first, when you screw in pedals, give the thread a bit of oil to try to prevent the metals from exchanging ions.
Then, and here comes the repetitive part, each time you fix something unrelated on the bicycle, take a wrench, give the pedal a nudge so it is no longer tight, and tighten it up again.
You don't need to tighten it hard. So if you are a strong, independent, fair-skinned, but not pale, okay, perhaps somewhat pale, computer scientist like me, and do this a couple of times a year, it should untighten with a little nudge, no trouble at all. The whole procedure takes 10 seconds per pedal plus two minutes to find the wrench and put it back.
The fun thing about pedals is that they turn around as you pedal. And if you think about it, they don't turn the same way with respect to their axle, since one axle is pointing to the right and the other to the left.
Now someone, and I suspect this happened early in the history of the pedalled bicycle, figured out that the spinning motion is great on the right side as it will tend to tighten in the pedal screw. At least when you pedal forwards, which I think we sort of standardized on.
But on the left side, the spinning motion will tend to unscrew the pedal. So on the left side, the thread is flipped so that it also gets to enjoy this tightening goodness. As a consequence you need to wrench the pedal the opposite direction on the left pedal - it has a links (left) thread, not a right one.
So this is why you don't need to tighten the pedals more than a gentle nudge, despite the forces involved in pedaling.
It also means that left and right pedals are not interchangeable. They are usually marked with L(eft) and R(ight). If you don't pay attention to this, you can easily destroy the thread on a soft aluminium pedal arm.
As for the wrench itself, back in the day, there used to be very little space between the pedal and the pedal arm so people would have special, thin pedal wrenches. Combine that with stuck pedals, and you would be sure to have a sad experience.
But all the cheap pedals I've bought over the past 15 years have had plenty of space for a standard 15 mm wrench/spanner, which I also use for the bolts on the back wheel axle. So no need for special equipment.