Doing any foolish mistake with your site can be costly. You should be careful what you are doing when promoting your site. For eg, you can have hidden text or links on your site without you knowing and you can be penalized. If it's not a mistake, you could be linking to websites that aren't good anymore, hence devaluing your site. What should you do? Well, you can't do anything about competition neither algorithm change but you need to monitor who you link to and ensure that your site is clean everytime.

Links on as many similar and related sites are still highly valuable to get top rankings and you should constantly get them regularly because that's the core building block of good placement in the SERPs no matter what and to outrank your competition, that's what you should do. And you can be sure that good quality links will still be important in every algorithm change. With the search engine algorithm changing, it can become more complex to figure out how to get top rankings or maintain your existing ones.