That's a good start, however ..... I hate it when people say that, don't you? I think that you are about to run into problems in terms of keeping your fire going. Depending on how deep the snow under your fire is. Depending on how deep the snow is and the situation,you should dig down untill you hit dirt, then lay your fire. Otherwise the snow underneath your platform will melt. If you cannot do that - for whatever reason - then the platform needs to be as thick as possible. If you are doing an emergency rewarm then what you have done is absolutely the right way to go. Now go and do it again. But this time do it without the cotton wool. Use only the materials you can find at your chosen site ( give you a tip: Silver Birch is the Rolls Royce of tinder. The bark, shaven or crumpled will ignite readily from a spark.)