Ok I am not sure quite what you mean but I will have a go.
How about sorting out your material into colours. That way you have the material sorted out as to the meaning.
Yellow = Wind, Divination, Creativity, Air, Movement
Could be used for helping someone move on, air travel that sort of thing, even to losing weight. Use it to support a spell that requires movement, changing things that sort of thing.
Red = Strength, Courage, Vitality, Fire.
Could be used for spells to do with finding the courage to do something, to provide strength to the spell you are making. Remember Fire is not always destructive it can provide comfort as well.
Green= Growth, Prosperity, Faith, Health
Could be used as part of a spell to aid health matters, to attract wealth, and again to support a spell.
Blue = Water, Peace, Healing, Joy, Contemplation
Could be used for bringing peace of mind to a situation, to find joy in something, used to support a spell like a spell for healing.
White = Protection, Purification, Innocence
Could be used for any and all spells.
Patterned material is also good you can select a material that has several colours to correspond with the intent of the bag.
Maybe the material has flowers on it find the correspondence for that flower and work with that. eg Red Rose Love
If it has things like animals on it work with the meaning of the animal eg Cat= love, indpendence, Butterfly = transforamtion that sort of thing.
You don't have to work with what the colour represents you can have it as a back up to the spells intent. My sachet had colours that added meaning to the spell I was making. I tend to think of what the spell is for and work with how I can strengthen it by using colours that do just that.
For example I want a spell to help someone regain their inner peace. I would probably use a blue material or maybe one that had a lot of blue in it along with say purple, white and yellow. It could be a flower design or one that is abstract.
Also think of the person you are making it for that helps a lot. Of course if you are selling them you would work on the intent of the sachet rather than the person.
Making small square or oblong sachets is probably the easiest. Cutting a circle and making a border around it then using a gathering stitch you can make a bundle sew it up tight and use ribbon to secure the sachet and make it look attractive. On plain sachets add a decall to liven it up a bit.
Is that what you meant how to use the material according to its colour etc? I always find simple is best it usually works out better as well.