It is very natural to want to use the heaviest bands available to get as much resistance as possible.However, a better strategy would simply be to buy the red, green, and/or blue bands and then combine them together if you need more resistance.
This is because the silver and gold bands are extremely strong, and you won’t be able to reduce their resistance level if you need to.
Just like working out with weights, it is better to have several 10 lb plates to work with instead of nothing but 45 lb plates – you have more options. The same applies to bands.
We usually recommend 1 red band and 1 blue band if you are just getting started. That gives you 3 resistance options. Adding a green band gives you 7 resistance options by combining bands.