A lot of us who start seeds inside use a grow light. I got mine last year, and my seedlings grew so much better. Money is always tight, so mine are inexpensive ones. But they were totally worth the cost.
I was hoping to improve the amount of light so I surrounded my seed station with aluminum foil. It did seem to help.
Yesterday I watched a YouTube
video by the MI Gardener on increasing your light by 75%. I was convinced. I removed the foil. I had some foam board and some poster board left over from some
project, or other. I put it up and I do think it makes a difference. It took a couple of minutes and cost me nothing. In the future I will be making some modifications to make it better and more permanent, but for now since I'm in the middle of the seed starting season this works great.
The MI Gardener guy didn't talk about foil, but he did mention mirrors can create hot spots like a magnifying glass, and shouldn't be used. He also said a mat white works better because it directs the light. ( Kinda what he said). Anyway I thought it was worth a share.