To concoct something that is easy, add a little of this and a little of that, but to really sequence your class that takes time and a lot of effort and a good deal of intuition.
I am in my second year of teaching and I was fortunarte enough to have had a very good teacher who always told us how she sequenced her class and why. During my teacher training I had a trainer who emphasized sequencing and the sillabus focused on this aspect a lot.
A few recommendations from my side: usually there is a linage connected to the style of yoga you are doing, stick to that style and the linage and what they present as their form/sequence in the beginning, you can later on start to add aspects which you feel is your own and which will make your class unique.
Here and here are links to the issue of sequencing that came up previously on the Forum with great advise. There are other posts as well and perhaps doing a search will reveal them to you and some more gems. 
Good luck, it will come to you, just go on and do what you intuitively feels you must do, it is usually the right sequence.