We use social media for promoting our products and service,I may say Twitter is not enough not unless you have thousands of followers and re-tweet it and buy the service or products. As well,it depends also of what are you promoting with. You can post in any social available for your products or services you want to offer, the more the merrier. I rarely use twitter because only few friends I have there who followed me and there is not interesting for me in twitter actually. I know twitter is where most billions people is but,I don't get it.
Promoting your product its should be limitless and it also depends who is your customer target, and what are you promoting. There is a lot of marketing being introduce in the market nowadays but not all product is foreveyone.there must be specif target customers.