Hello,
there is no universal right answer to that question.
But if I was in your place, I would figure out a formula for your own TIME.
At the beginning, when everything is undone in your startup, you have to take care of as many things as possible yourself.
Then, there's that point when you realize that certain things become much more positively impacted when you do them yourself, and others much less.
Adwords is such an universal tool, it fits the requirements of almost any company. But therefore it also became a very complex tool, as its been said already.
That doesn't mean that you can't try DIY. All the knowledge, information and even free seminars are there. You can start Adwords on a small test scale, trying to absorb as much knowledge as possible and risking little.
Therefore, I disagree this question is answered by means of CPA, as much as it can be answered by means of TIME.
Back to my first argument, if you find yourself providing VALUE to your company on things that are high impact for your efforts, you will sooner or later realize that an Adwords specialist is going to save you time and of course, do a better and more specialized work as yourself.
So, SOLUTION: it depends on your TIME and how valuable (or impacting) it is vs the cost of having this outsourced.
Still, if the outcome is that is better for you to DIY for some time, I encourage you to ask questions, for example in the Adwords forums, or calling a specialist for more strategic or complex matters within Adwords, hence save you TIME.
Hope that helped!

Hello,
maybe something not yet mentioned is to actually protect your brand by registering it (through your national registering agency, OHIM or WIPO, as examples).
You should know if your brand should be registered by calculating the profit driven by brand traffic vs registration costs.
Sure, advertisers will always be able to bid on your brand, but as you register it (first) and let Google know you want it to be restricted (second) you will succeed in having many advertisers using your brand in their ads, to have their ads disapproved.
They might then change the ads, but won't be able to mention your brand in their text ad anymore, hence become a worst Quality Score. With a worst QS it will be less profitable for them to keep bidding on your brand intensively.
I have successfully implemented brand defence strategies for my customers, increasing profitability on both paid and organic channels.

Hi, it is a rare case, when "active" keywords don't give a single impression for a long time. It is well known in the Adwords platform that most of such keywords are considered "low search volume" and are simply switched off, that is, they don't even participate in the auctions.
So, before the first impression the bid should be some average of what your campaign or adgroup bid is, once you get the first impressions you will get a sense of either under or over bidding by checking the position. Before that first impression, it truly isn't very critical the bid you assign as long as it is in line with the rest of your group/campaign/account.