Exact keyword with Broad keywords in title?

Quick question. If I use the google keyword tool and let's say "how to use iphone" exact keyword gave back 10k local searches and low competition. Would my blog article still do good in serps if the title was "How to use your iphone"?

Would do okay, you often see search results like that, and you'll see the keywords bolded and 'your' left out. But I always like to make sure i use the exact keyword, just to be safe, even if it sounds stupid. Then underneath you can do a subheadline to make it make sense, like:

How to use iPhone
A step by step guide to using your iPhone

Gotcha. Also, does using h4 tags benefit you as much as h1? I ask because my template's h1 tags are humongous although I know I can change it, so most of my content is using h4 and paragraphs.

In my personal opinion (which many will disagree with), I don't think things like h4 tags matter. It could be the best written page in the world, a ton of backlinks to it, and google is going to say "Oh sorry, doesn't have a proper h2 tag, let's rank him lower". That being said, I like to have the title and and h1 with the keyword, as well as in the alt tags of an image somewhere.

I'm currently #7 for a term that has 150,000 searches per month and I just recently put the keyword in the top h1 heading. I just wrote the page for the reader, not for search engines.

But to your case, I'd probably do the first one a H1 and the rest h2. That's usually what I do when I write articles.

Gotcha, so now I need to go in and modify my CSS code, and replace my articles