What Niches really need help with digital advertising in 2018?

You'll need to do your research. No one can answer this for you, though many will give answers in an attempt to do so.

So - at the risk of repeating myself - you will need to do your research. No one here is going to do it for you - without being paid.

"Are there any others that are really not using advertising correctly and could use a consultant's help?"

Yeah - most!

The list of niches who do not need help would be very short.

Your local Churches, schools, and local businesses in your area, are all in need of media exposure. They all already have an advertising budget. If you can show them new ways of making that budget stretch further by using internet marketing, then you will definitely be the consultant that they will want to do business with.

It's up to your to pick a viable niche and carvre out your market share in your niches of choice. Pursue your passion, and the money will follow you wherever you go.

There are só many that it's hard to pick one...just try google trends to see what's trending at the moment

Most of the small and medium businesses that don't have a specialized person to run their ads are wasting money every single day on ads..and even the large ones..

I remember I saw an interview with Neil Patel and he was telling a very interesting story...At one point he used to manage General Motors' marketing spent, their finance division, and they were spending 5 mil on ads every month but 2mil were not producing anything..not even a single dollar in sales...

Also, nowadays to be on the first page in Google is harder and harder, so people pay some of the ads just to maintain their visibility on the search engines no matter if they perform well or not..

If we're talking local businesses, I suggest going after medical and legal practices, real estate agencies with 5 or more agents, Specialty medical clinics (Hormone replacement, cosmetic surgery, weight loss, etc.), moving companies, and roofing contractors.

These local businesses all have a high value associated with each lead you bring them. Medical can be in the 10's of thousands in some cases. If you successfully market an accident * injury attorney, a single lead could be worth millions.

People running local businesses in these categories I mentioned who figure this out do very well for themselves. They're perfectly happy paying a $1-3k month retainer in the US if you can make their phones ring. If you actually know how to be effective in digital marketing, you can keep clients like these for years.

Local business and real business (anything that provide something in real, not digital stuff).

Concentrating on local markets is good idea if you have the technical skills required for the tasks. Its a useful place to start because the opportunities are almost endless and, while internet savvy small businesses are growing, there are still many that are put-off by the internet and learning the skills needed to make it a worthwhile endeavor.

Some of the skills valued would be SEO, site or landing page creation, traditional online advertising, video ads, YouTube ads, etc. Selling niche-related keyword domain names also has its adherents.There are entire subniches on affiliate marketing platforms that are devoted to offering platforms and programs that can streamline offering advertising for small businesses. It my be worth your while to check some of them out.

These skills will always come in handy and, as the previous posters have pointed out, you'll probably need to explore these local businesses to find out which businesses are the most enthusiastic about your ideas. Some people get their start by doing work on spec or doing a test ad or website.

Best of luck, whatever you decide.