Amazon Niche blog Basic to Advance questions

Guys, Here I'm sharing few things. First I go to Amazon dot com and then i picked up the Sports & outdoors sections.

And now here are a lot's of niches also. Like:

fitness, camping & hiking, cycling, winter sports, golf, running, swimming, football, sports technology, rugby, water sports ...

Then, I go with camping & hiking . and now here are also a lot's of niches like:

tents, outdoor clothing, bags & packs, sleeping gear, camping furniture, cooking equipment, knives & tools, lighters & fire starters

So,
1.Sports & outdoors sections
2. camping & hiking

Here, I've one question, Should I go with camping & hiking ? Can I tell this one micro niche or authority niche. As well on this there are also a lot's of niches. I've already shared ..

Let's go to become more specific. Let's go with

Knives & Tools. And here are also many niches like:

multitools, folding knives, pocket knives, axes, cases and bags, lighters

Should i go with "Knives & Tools" parts or the more specific niches. Here is a question,

Knives & Tools, Is it micro niche, specific niche or what?
well then let's go with

Pocket Knives. So, now there are no more niches. I think this is last one. So, Should i choose this one?

Or what i need to choose ?


How you do Keywords research for your niche blog (Amazon niche blog) ?
1. Primary keywords
2. Secondary keywords
3. Long tail keywords
4. Long long tail keywords

Whats steps you follow to find out your best keywords for your niches?
whats seo metrics you follow to find out the best low completion keywords ? Like: PA, DA, PR, Site age, Backlinks profile of your competitors