BiasTape is very practical help in sewing. Far too often it happens that you don't have it at the moment you need it... or there is no exact the one at the shop you were thinking about. That's why I have made my own BiasTape far too often.
First of all you need to decide how wide you need it to be. If you use just pen, ruler and sewing machine; the width can be anything. The most important thing is to cut it in 45 degree angle. It is possible to cut it in crosswise or lengthwise grain but sewing will be more challenging and the BiasTape won't be so stretching and malleable then. I cut crosswise or lengthwise grain only then when I don't have enough fabric to cut in 45 degree angle.
I recently bought Bias Tape Maker Set. It includes an awl which helps you to pull fabric through tape maker. My set includes four different size of tape makers.
Feed the bias strip wrong side up into the wide end of the tape maker. You can see the hole in the maker. The awl fits in that hole and through it you can feed the bias strip further into the other end of the maker. Bias strip comes out as folded from the maker. If you don't have an awl you can try out for example tapestry needle or small knitting needle.
My set included pins too. They are there to pin the folded bias strip on the ironing board. I found that pinning difficult because then I am not able to work with "free" material. I don't use the pin. The iron holds it as much as needed. But try out pins; it might be easier for you. I just am awful with pins. I survive better without. I use them very rare.
Remember to keep iron close to the tape maker when working.
When you iron the folded bias strip it turns out BiasTape and is ready for use. It is pretty fast. In my case it is also fastest way to get BiasTape. It takes more time to go to the BiasTape shop than make enough of it.
