Raju, points below are informed by my work in building Cisco's 'Enterprise IT Business Specialist' curriculum. The audience here is mainly Career IT infrastructure professionals (architects, team leaders, specialists etc.). I'd expect our conclusions to have relevance towards Marketing, HR, etc. as well).

We researched various roles within the corporate IT community today, as mentioned in job descriptions/postings and anticipated within 2-3 years (to include cloud, analytics, security, etc. and cross-domain responsibilities). Analysis drove us to 5 categories of skills and/or opportunities (& mistakes).

1. Business acumen (process)
2. Financial
3. Organization change (adapting)
4. Internal (awareness about own organization and/or context for role)
5. Communications

Here's a few 'mistakes' by category:

• 1) Business Acumen/Process (mostly designing for typical/standard activity -- underestimate the volume and nature of exceptions. This can apply to digitization of any manual or hybrid digital/non-digital process. Exceptions get kicked out and handled without the requisite skills, controls, data inputs, etc.)

• 2) Financial - for the CAPEX and OPEX shift -- not anticipating OPEX charges that will be critical over time. For instance, not all XaaS monetary flows are going to based on volumes. There could be $ for training, transition/data migration, data integration, reports and other customer or project-specific situations). So, OPEX isn't always a straight line ongoing.

• 3) Org Change - Mistake -- not planning for stakeholder support or specific actions to re-establish momentum after an initial rollout. For ongoing adoption and consumption, there should be a drumbeat of user encouragement or on-boarding (of course, supported with IT or specialist attention as a booster)

• 4) Internal - become aware of other initiatives or activities that may conflict with a specific action you own. Contention, risks, extra complexity, etc. peak when companies try to force too much into 'end of quarter' or available windows for operations. Another internal 'mistake' happens when IT leaders don't make their teams fully aware of successes they may have realized, in gaining confidence or support from their business stakeholders (peers).

• 5) Comms - Esp. for technical professionals -- when informing business people about situations, impacts or recommendations... Give the result or outcome first, and then support with details. A top down information flow is most likely to be received more favorably than other sequences. Also, early in the communications, clearly state some business statistic or artifact which you're read or heard from a business stakeholder (must produce rapport with recipient of the information, each time there's an interaction -- otherwise, questions about trust and credibility will creep in).

Please reach out directly as you wish -- I'm glad to share further insights and/or examples.

I think basic financial training should be a must for leaders of any domain. In my experience, I have seen leaders from various domains struggling with financial matters. It is true, that they don't have to be expert on the subject, but they should know the basic stuff. And I think this is because of lack of training. Finance is considered as boring, complex, subject to fear and hard to understand ( At least that's what I heard from a few I met). If they were taught properly, they can get this too, like any other subject. 
Few things where I have seen paying them big price without knowing the basics are planning, forecasting and managing the budget.