Your methods seem to be efficient and workable but one thing left unmentioned is the time factor and that even after adding so many links to your website, some degree of patience would be demanded, especially if your targeted niches are so competitive which are filled with thousands of domains and sites, powered by many one way links online.
Webmasters are using a variety of names like their sites are in Sandbox, some temporary ranking filters or facing rankings drops or even dances and usually these events happen to the websites which are newly launched and targeting very hot terms. Some weeks and months of work combined with patience need to be gone before results are gained.
You need to make quality and relevant links for your website and have some patience, certainly you got the ranking. If you want exact solution Pm me your website's URL and keywords. I'll suggest you the best method according to your need.
I suppose all mentored above is correct and can be used for that purpose. Just in any case you need to understand that if there is very commutatively niche you will need to spend a lot of time and put more efforts.
Actually, all items you listed can affect your SERP. However, for more faster site SERP, you must improve your site content as well. Do a unique and quality site content to invite visitors to view your site. Through this way, you can gain more traffic which is a very big help in making your site more visible online.
I don't know why you did not get benefit out of blogs and forums. I have got the maximum boost in SERP from these two avenues quickly. But the only condition is that the blogs and forums should be relevant and to the topic.
The best way to build a strong presence in the search engines is to build a quality site. Use proper optimization techniques, social media tactics and viral marketing. Always strive to get links from authority sites in your niche. Most of all, build a great site so people will WANT to link to you.
Firstly you should know that it takes some months for getting results according to the competition on keyword you are working for. And the other thing is the quality of backlinks you made for your website using your methods. Note that its better that you make only powerful backlinks for your website using your above methods instead of making thousands of low quality backlinks.