How to increase the position of the site in search engines for keywords?

Question

Search Engine Optimization

Tell me plz!
There is a website, the agency was engaged in promotion ... They refused .. We decided to work on our own ..
After another conversation with the agency, positions on requests began to fall sharply ..
1. As I understand it, they can influence this themselves?
2. How to maintain the position of the site on our casts?
Anchor and non-anchor links have been placed ... made turbo pages, etc., but there is no result yet ((
there were no changes on the site (online store), except for news)..
3. How do the agencies themselves maintain positions by keywords?
because . on the site while working with it were carried out minimally .. paid links were not posted either .. so it became interesting and not entirely clear ((

Answer 1

Decided to save, get a fall. This is fine

Answer 2

Rental links are the perfect leash for such clients.

Answer 3

Everything about this topic is great.

After another conversation with the agency, the positions on requests began to fall sharply..
As far as I understand, they can influence this themselves?

do you understand that no one will answer your questions here and at most they will throw off a link to manuals for studying SEO?
In order for a specialist to be able to answer, specific information and analysis of your site, niche, core family, competition, optimization, etc. is needed.
Having decided to promote the site yourself, you have chosen a path in which you will have to set up a lot of experiments, gain experience, and most importantly , apply it to your store. This usually doesn't end well.
But anyway, good luck :)