One of the biggest problems I find with SEO is getting clients to implement my suggested course of action correctly. Back in the days where I served as in-house SEO, there were several of us in the office in charge of going out there, researching the latest trends, doing competitive research and coming up with things that needed to be done. Some stuff, like link building, we would then be directly responsible for ourselves. For any changes to the site, though, we'd require authorisation from The Powers That Be, plus actual hands-on implementation from developers or designers. Perhaps unsurprisingly, the stuff that was our sole responsibility was always implemented without hassle, whereas the inter-departmental stuff would often involve much negotiation, troublesome misunderstandings and plenty of going back and forth. The rules of good SEO, often conflict with the laws of good design. They can require a lot of work from developers who may be already overworked and underpaid. This can be hard to get done if people don't understand why they are doing it. Bosses may demand guaranteed good results instantly (which, as we know, is not the way the SEO cookie crumbles) and become disappointed when denied, putting a damper on any further much-needed work.
The sad truth is that SEO is still considered to be pretty obscure in the eyes of most people. While there is growing awareness in companies that it exists and needs to be done, it's often still at buzz-word level. The nitty-gritty of it is lost on most non-SEO professionals. What's worse, there are people out there who think they know about SEO but are walking around with knowledge that may have been accurate several years ago but is now grossly out of date. This creates a need for solid internal PR to advocate the need for search engine optimisation, its changeable nature, the timescales involved and the need to make the changes suggested by one's marketing department quickly and accurately. In my own personal case, I found that after I gave a brief, simplified talk about the ins and outs of SEO to the rest of the staff, people were far more willing to get things moving. A more in-depth talk with several of the developers helped even more (as did my promise to include them in my business lunches!).
Since those days, I have worked as an external consultant and have found that while my advice is more likely to be taken seriously by those who commissioned it, it is even less likely to be followed correctly once I am out of the picture. As any consultant will tell you, this is incredibly common. Considering the fact most companies are happy to shell out significant amounts of money in order to get quality SEO advice, this spells out a major waste of resources for those companies that then fail to follow the advice they paid for.
It can be hard to educate your staff about the need for implementing an SEO strategy if you are not an expert on the matter yourself but any worthwhile SEO consultant can help with staff education or recommend helpful resources. If there are certain key staff members or departments that would be in charge of implementing changes, it is important to make them understand not just the how but also the why: the reason why those suggestions were put there in the first place. This prevents the mistrust and doubt that could otherwise manifest when you bring in external advice. The art of achieving high rankings in search engines is a subject that is broad, deep and always changing, but the principles behind it are simple enough to be conveyed to any business or technically minded person in easy to understand terms. If you take the time to do this in your own company you will assure that you are making the most of any consultancy services you're paying for.