QUOTE: “An infinite number of niches are waiting for someone to claim them. I’d ask yourself where you want to be, and see if you can find a path from a tiny specific niche to a slightly bigger niche and so on, all the way to your desired goal. Sometimes it’s easier to take a series of smaller steps instead of jumping to your final goal in one leap.” Matt Cutts, Google 2006
Alt text (alternative text), also known as "alt attributes" describe the appearance and function of an image on a page. Alt text uses: 1. Adding alternative text to photos is first and foremost a principle of web accessibility. Visually impaired users using screen readers will be read an alt attribute to better understand an on-page image. 2. Alt tags will be displayed in place of an image if an image file cannot be loaded. 3. Alt tags provide better image context/descriptions to search engine crawlers, helping them to index an image properly.
QUOTE: “You heard right there is no duplicate content penalty… I would avoid talking about duplicate content penalties for spam purposes because then it’s not about duplicate content then it’s about generating in a very often in an automated way content that is not so much duplicated as kind of fast and scraped from multiple places and then potentially probably monetized in some way or another and it just doesn’t serve any purpose other than to gain traffic redirect traffic maybe make some money for the person who created it this is not about content that gets really sort of created for any kind of reason other than just to be there so I person I don’t think about it as duplicate content there is just this disparity it’s the same thing as saying that maybe we created gibberish is some sort of a duplicate content of words but otherwise also exists like I I would really separate those two issues because the things that Aamon led in with URLs generated on WordPress and the things they were going to discuss today later maybe about e-commerce sites and so on I wouldn’t want people to confuse those two.” Andrey Lipattsev, Google 2016
You can confer some of your site's reputation to another site when your site links to it. Sometimes users can take advantage of this by adding links to their own site in your comment sections or message boards. Or sometimes you might mention a site in a negative way and don't want to confer any of your reputation upon it. For example, imagine that you're writing a blog post on the topic of comment spamming and you want to call out a site that recently comment spammed your blog. You want to warn others of the site, so you include the link to it in your content; however, you certainly don't want to give the site some of your reputation from your link. This would be a good time to use nofollow.
Ask for a technical and search audit for your site to learn what they think needs to be done, why, and what the expected outcome should be. You'll probably have to pay for this. You will probably have to give them read-only access to your site on Search Console. (At this stage, don't grant them write access.) Your prospective SEO should be able to give you realistic estimates of improvement, and an estimate of the work involved. If they guarantee you that their changes will give you first place in search results, find someone else.