I keep pj soaked cotton balls in a mini Altoids tin sealed with electrical tape and it hasn't dried out in over a year. Try sealing the tin.

I have had a lot of success with pj soaked cotton balls.
After reading numerous how to's here and some trial and error I've found it key to really tear and fluff the fibers. The fibers are the wick and the pj the candle so to speak.

Picture the tinder bundle with the fluffed cotton ball in the center in front of you with your back shielding the bundle from the wind.
I hold the edge of the firesteel to the cotton ball and while pressing firmly with a firesteel.com striker I pull the firesteel towards me, away from the bundle. The strikers is stationary and angled so that the sparks aim at the cotton ball.
Using this technique the cotton ball has not failed to light.

I'm no expert so it takes a couple of tries when the weather is not ideal but being patient and sometimes uttering words I would not type has worked for me.

Good luck!

I bought some small plastic vials about matchcase size and put my PJ cotton balls in them. I pack them in there tight and put on the lid. It is water and air proof when closed. I have tried the cotton balls after a year packed like that and they worked perfectly. Since they are packed in there, I use a small stick to pluck them out when needed.

I learned to carry at least 3 fire making methods with me. I carry the Light My Fire ferro rod, some strike anywhere matches in a very old Boy Scout matchsafe and I carry a Zippo lighter, freshly filled before leaving home. I usually have a mini Bic and perhaps an aluminum Sparklite also on me somewhere. I yake the PJ cotton balls and the TinderQuik with the Sparklite. So, fire is not a problem.

I store my vasoline/cotton balls inside plastic soda straws. Hold one end closed with pliers and melt it with a match. Fill with cotton balls (cram them down in there by rolling them, pushing with toothpicks, etc.) Then pinch the second end closed with the pliers and melt that too. I have several I made like this years ago and they are still sealed. However, I have not cut one open to see how the cotton balls inside have faired. I should do that. I had assumed since the straws are still solidly sealed that things inside would be A-OK. But now you made me think, "An assumption is the first step towards a screw-up", and I need to VERIFY that things are good inside my soda straws. At one time I made a point of grabbing and extra straw or two at fast food places - especially if they had those large over-sized diameter straws.

Are you using enough magnesium shavings, IIRC you need a pile about the size of a quarter and collected on a thin solid pan, a dry leaf, pc. of paper, in a cotton ball nest, etc.

weird

Something I don't think anyone mentioned yet. Make sure your tender is very fine. You can just pull out long blades of dead grass, weeds and start a fire, but I make my tender balls with that material pretty shredded up AND able to be transferred to actual fire area.

I can't stand Magnesium shavings. Its like a 1 outta 10 deal for me unless I have it on some paper first. Sparks never land on it.

Again hold the striker, pull the firesteel back towards you, with a lot of friction applied.

Never had PJ soaked cotton balls dry out. Like many others here, I carry at least 3 different methods for starting a fire, and multiple tinders as well. You may want to consider a Blastmatch, it works very well for me. A little larger than most ferrocerium rods with strikers, but worth it to me. The Blastmatch can ignite dry grass and leaves, it produces such large and hot sparks. In addition to PJ cotton balls, I like the Esbit cubes and Sure-2-burn. Crumbling an Esbit cube will allow it to ignite from sparks. Open the Sure-2-burn and the contents will take a spark. Tinder quick is also excellent and available in most outdoor stores.

And with all that said, practice, practice, practice. All the best tools and materials in the world won't help if you don't know how to use them, in any environment.

try a cotton ball size amount of compressed OOOO steel wool...works well with primitive flint(chert) and steel striking also...

The OP doesn't give his location, but he should move to Southern California. A glance at either the skyline or the headlines will affirm that it is quite easy to start fires around here right now.

More seriously, I have always found matches to be quite reliable, especially if you upgrade to the stormproof variety. I agree, redundancy is a good thing when it comes to fires.

hold your striker steady and pull the fire steel away from whatever you are trying to light. it is easier to aim the sparks that way IMO.

i have never had any trouble lighting cotton or lint. usually on the first try.

sometimes a slower scrape works better as it seems to generate more sparks and is somewhat easier to control.

I have not tried to light dry grass or other tinder with a firesteel. I have tried to light charcoal lighter with it unsuccessfully.