So here is this PR4 website, 25k indexed pages and around 5k backlinks. My job now is to get it on page 1 of Google for ~1500 keywords, they are long tail, many of them over 5 words long so it won't be hard to do this with anchor text backlinks but I want to know what others think. I want to know what is the best and safe way to do this. Isn't it going to harm the website's ranking getting thousands of new backlinks with hundreds of different keywords?
Hmmm.... I think since your website already has some weight in google it will not harm it too much. With that being said I wouldn't fire on all cylinders right away I would slowly lead up to the 1k backlinks a day. For example, start off around 500 backlinks a day and slowly work your way up
If you get back links in no time they you may be under the scanner. But if those links are all from white hat methods then it will not be a problem for you anytime. Only black hat techniques get you penalized
5k backlinks for a PR4 websites is way too low. Don't worry about getting penalty, you should be fine. BUT if you put those 1500 keywords into your website "keyword" tag you'll be banned for life! Google doesn't like more then 15-20 keywords...
Why not create individual pages that includes groups of the keywords you're trying to rank for? Don't overdue it - make sure that you keep a keyword density between 3 - 5%. As someone stated above, you already have authority in the niche so should be able to add the content and rank fairly easy. I am not quite sure what you mean by "Is it going to harm the sites ranking getting thousands of new backlinks"? Where are you getting all of these backlinks? Are you talking about spamming to dofollow sites to get these new pages backlinks? If so, I would highly advise against doing that. As stated above, you seem to have some authority in the niche, so why not just create new pages or add a blog targeting the keywords you want to rank for? Gradually send relevant links to these internal pages and you should start ranking. If you're doing this for a client, I would suggest doing it correctly so that it doesn't come back to haunt you. Also realize that SEO is not something that can be seen overnight, unless you own a very authoritative site that google loves and is publishing content the second you put it on the site. Hope this helps.
It is not easy to say "Ok I want to ranked on those keywords". You should first analyze the competition on this keywords plus their monthly global searches. A keyword with more millions of competitors is likely to be hard to beat.
Thew website is a E-commerce one with thousands of products. All the 1500 keywords will rank for product pages or brand pages on the website not to the home page. I know the results can't be seen overnight, I just never did it for so many keywords. I'm thinking about blog commenting, the key-phrases have very low competition so they won't need many backlinks to rank better, many of them are already on the first 5 pages without any backlinks.
I'm not sure if I remember correctly, but I think that if you post a comment with a URL that isn't a site root, Akismet automatically flags it. Might want to experiment with that to be sure. It still helps without a doubt to get links to individual pages, but these days for long tail terms, Google favors content on domains that rank for relevant short tail terms so even if you just keep link building to your home page, you're in good shape.