Other than finding site owners of good sites willing to include your link within the content on their site without an exchange, the kinds of links you are describing aren't really your best bet in terms of high quality links that will impact your standing. While these tactics aren't necessarily bad practice per se, they each have their cautions and they won't earn you especially potent links.
Watch out for the link exchange route- only do this within your niche with sites that have an indisputable relevance and connection to what your website is about. Forums are great to participate and learn in, and you stand to develop some strong relationships that way, but don't count on links within the forum to benefit your link portfolio. Same for blog comments even if they are follow links.
What is raising my curiosity the most here, is why your client has website in an industry she or he doesn't know enough about to create content? Is this a new business endeavor in a field they have yet to understand or participate in?
Here's my real answer to your questions:
It's not all about links. Having a successful business and website is about offering something of value.
My best suggestion is for you both to spend your time developing knowledge and confidence to write about kite surfing and related topics. Read like crazy. Research and learn. Gain knowledge and build opinions and a viewpoint to write from. You can write about related topics also- what are kite surfers interested in? Great locations for kite surfing, other related water sports, equipment, lessons, stories about kite surfing experiences, dolphins, beaches, dangers.....
Creating compelling and helpful content and publicizing it on your social accounts and anywhere else you can will give your readers an opportunity to share and link to your site is the way to earn quality links.
Hope this is helpful, Juan.