What is the best system for numbering your photos?

I think the number just starts over again. On my digital camera and when I down load them on to my puter they delete the old photos with the same numbers.





Happens with the cell phones too I think. I have two cells of the same type and one different cell.(different people using them, but I get the pictures to manage and save)





It takes a long time to title them separately and I can never remember if I use the same name sometimes or not.





I think most the time it asks if I want it to write over the photo (can't remember exactly how it asks this), but usually I can't remember if it's the same photo or not,and I think sometimes it just writes over them anyway.What is the best system for numbering your photos?
Well, usually it IS better to name them.. just keep track of the names..


Makes it easier to know what is actually on the picture.What is the best system for numbering your photos?
i go photo1 photo 2 ect





then i go photo 1a, 2b, 3c,





ect