I was wondering if i would get penalised for repeating a certain keyword in my descriptions, even though that keyword is part of a phrase. For example for the keyword 'backpacks' which would be the best description: Backpacks, jansport backpacks, school backpacks, roxy backpacks, kids backpacks, leather backpacks, north face backpacks etc. or omitting the word backpack from the keyword phrases. Backpacks, jansort, school, roxy, kids, leather, north face etc. I hope this makes sense. Thanks
Repeating keyword backpacks could be considered as keyword stuffing and you might not get an advantage you are looking for. The second option is well and you can prefix and suffix the whole possible combinations with backpacks. for example this is acceptable Backpacks, jansort, school, roxy, kids, leather, north face back packs. this can give u position on key pharases like Backpacks Jansort or Jansort Backpacks and others. I hope this helps.
If this is going to be for the META keywords tag, the first one should be fine, especially considering that the META keywords tag is all but worthless anyway. Focus on using your keywords in your page content - your headings, paragraphs, list items, link text, and so forth (not to mention the targeted anchor text on pages linking back to your own pages, whether they are from other pages on your site or from other sites entirely). That's where the real value of your keywords lie anyway.
Dan Has a valid point. Its essential to have all you are targetting in your text, or its all of no use. The keyword in the link back helps a lot.
Thanks, would i get penalised by search engines for using a specific keyword too many times in descriptions, or opening paragraphs. Is there a guide amount of times that a certain keyword should be used?
You won't be overtly penalized unless you're deliberately stuffing the description with keywords, but the value of those keywords will diminish. The best you can do is read your META description copy from Joe Sixpack's perspective (that of an average reader). If it sounds spammy in that context, it probably is. To be honest though, I'd probably aim for no more than two or three instances of the keyword in the description. After all, you do have a 160 character limit to play with.
Dan is correct, you can play around 160 characters max. Also repeating keyword too many times doesn't help unless your content really demands it. Like All SEO chaps, I would suggest to write naturally on your page like its for your users and you want to provide a healthy information to your visitors.