Its important to clarify a bit about seo plugins.
They are not the magic tools that will automatically rank you higher, but they may help to target keywords, suggest the titles, and tune up your post to get better results, (provided you know you are doing).
The Yoast plugin mentioned above though, also does a great thing is that is submits the sitemaps directly to search engines whenever you make a new post, thus helping it index faster with search engines.
I personally use ‘Google XML Sitemaps’ for this purpose, but that’s perhaps just a matter of personal preference.
One important thing to know about indexing, is that submitting the sitemap to google, wont automatically guarantee indexing of your content.
If the site is fresh, and also has been having some low quality content on it, then the indexing might even take weeks.
So I would advice just to focus on quality, and get a good amount of patience. That the way…
Cheers ??