Everyone that has responded to this question - has provided sound advice - and it is also clear that many have experienced the good, the bad & the ugly with Digital Marketing. Keep in mind that our input is from a B2B perspective.
The #1 question that novices and inexperienced users need to ask is:
What are the solid reasons that Digital Marketing needs to be incorporated into their business and Marketing Mix?
If the answer is: It is fashionable/in vogue, a requirement in any business to succeed in today's competitive and brutal market or the old tried-and-true approaches aren't working anymore - then - that is not justification for integrating Digital Marketing into your core business.
Also - let's dispel the false expectations - avoid thinking that you simply need to put Digital Ads, Visual Posts, Videos and other tools into place - to bolster traffic to your website, reach a rich prospect audience (previously untapped) - build an effective position/brand - and count on Digital Marketing solely to take care of it - not going to happen.
There are three (3) fundamentals:
•Sound Industry experience – that speaks the language of the prospective audience.
If you are focusing on the Defense & Aerospace target segments (for example) – then make sure that you have subject matter experts that can translate your position, messaging and solutions properly.

•Market Programs expertise – whether you have an in-house team or leverage an outside source - make sure that there is a program framework, methodology/process orientation, documented plan approaches/techniques to assure program effectiveness.
Otherwise, your Digital Marketing Program may be a high-stakes gamble and miss the mark.

•Rich Contact Base – this is probably the most essential element – and must be based on Industry relationships that have been forged – not through acquiring e-mail lists or contact data-base subscriptions. The element of trusted source does not come easy. With it, you can gain access/entry to key accounts and start your campaign on the right footing. Without it – your program is lost in the noise.

That final message is the key to applying Digital Marketing to your business and the timing - will it be effective or will you be lost in the noise?
For our Clients - we do a deep-dive (called Homework) to fully understand their challenges, opportunities and/or problem set - which then provides insight to the right Marketing Mix - of which - Digital Marketing can be an element of the overall program.
Lastly - avoid being an "experiment in terror" - do Pilot Programs first - to iron things out - before you go full-tilt on Digital Marketing. 

On a different note - we leverage traditional and new wave marketing techniques  (hybrid approach) - for both our company's direct efforts and for our Client Programs.
Digital Marketing continues to be a staple - and we will continue to build upon it - as required - smartly.