How to increase SEO for established website

I've made a good start so far to the SEO, but the keyword I'm trying to rank for is highly competitive. These are my stats so far for the page I'm trying to rank

Ahref:
URL Rating - 29
Domain Rating - 47
Backlinks - 59,000
Referring Domains - 64

Majestic:
Trust Flow - 31
Citation Flow - 40

I was wondering what I should do next to increase these further. I'm currently trying to post guest posts on similarly ranked blogs within my niche to get some high-quality backlinks. Am I along the right tracks or is there something more I should be doing?

Also if anyone knows of any SEO packages that aren't too expensive that would help, please point me in the right direction

Some good ideas: Link

Guestographics should work really well

If your competitors are having big brand names or you are having high competition KW means you should have a high budget to beat them.
Get some press release, use Adwords, use local citations to beat them. Analyse on your competitors link building strategies. Concentrate more on your on page SEO & content quality. Get quality links from niche related sites.

You have to more concentrate on to get Quality backlinks is the way to get the rankings for High competitive keywords.

For, High competitive you have to build in high authority sites in the same time check your meta description.

As you mentioned 59k backlinks so you concentrate on your content firstly after that ON page methods.

And Niche relevant links will help you to get good results.