For any modern entrepreneur I`d suggest the sweet spot of cloud applications you should master is the holy trinity of these three killer apps – Linkedin, Salesforce.com and Google+ Apps.
In short these cater for the end-to-end requirements of a sales operation, so you can begin selling and closing deals.
Establishing successful sales teams is naturally a milestone you want to put in place as quickly as possible, and so having the tools as equally as quick as possible is one of the primary benefits of on demand IT.
Getting these three running gets you out knocking on doors, capturing prospect contact details and submitting initial proposals and even hooplah customer contracts.
As things evolve you can add everything else: E-contracting for speeding up return of those contracts, better e-marketing automation and social media publishing. These are also staples but the first three gets your beachhead established.