1. First things first
When you start investing, you cannot participate in the big deals that require a lot of money. It's the same with SEO. If your website doesn't have many rankings yet, then it doesn't make sense to target very competitive keywords such as "lose weight " or "make money online".
The big players in your niche have the high rankings for these keywords and they have several advantages (more back links, more visitors, more trusted by Google, etc.).
Start with very targeted keyword phrases that consist of 3-4 words. It is much easier to get high rankings for these key phrases and you will also get higher conversion rates with very targeted key phrases.
The more rankings your website has, the easier it will be to get high rankings for more competitive keywords. Then you can start to compete with the big guys for the more general keywords.
2. You have to be careful
There are many people who promise to make you rich overnight. Others promise incredible profits. The more aggressively you invest, the more likely it is that you will lose everything.
It's the same with SEO. If you use aggressive (and often shady) SEO methods then you put your website at risk. Aggressive tactics often deliver great results for a short period. Unfortunately, all of them also lead to massive problems with Google. Many websites have been banned from Google because they used spammy SEO tactics.
If you see offers like "thousands of backlinks with no work" or "fully automated SEO solution" then you should be very careful. In both finance and SEO, there are many snake-oil salesman. Don't fall for them.
3. Time is a factor
If you are young and invest your first dollars then you won't become a millionaire overnight. It takes some time to build your wealth and if you invest regularly, you will earn more than people who invest only once. If you invest too little, you won't get the same results as people who are serious about building wealth.
Search engine optimization works exactly like that. If your website is young, then it will have only a few rankings. You have to optimize the pages and the backlinks of your website and you have to do it regularly. The more time you invest in optimizing your site, the sooner you will get results.
