How much time do you'll take writing an email to your subscribers?

The answer to your question is very wide indeed.

This depends on the relationship you have already
established with your subscribers and just WHAT
you want to relate to them. So it may be just one
line inviting them to read a blog post or it may be
100 lines selling a new product you just launched.

So there are too many factors involved to even
give a ball-park answer.

-Ray Edwards

Get on some good email lists and review the length of their emails.

You will get a good idea from good examples how long it will take to write these emails.

The email depends on the list (different ones for different niche markets) AND the email message. It can be mid-length if I am providing some relevant help or information.
If it is a promotion, these vary depending on the product offer and calls to action.

For fitness and self-help type niches, I write some follow up encouragement emails to keep people engaged and working forward. I encourage feedback that way.

So for your question, it will vary depending on what you are targeting with your email.

[. . .what should I keep in mind to ensure that my subscribers are actually ones who'd buy from me and not just ones who'd just keep reading forever and thats it?]

-Have regularly scheduled emails; however, don't inundate them with emails.
-Don't have an offer every time you email them.
-Don't send them any content that is not related to their reason for subscribing.
-Send only quality emails; don't send them crap just so you can meet your scheduling requirement.
-Put yourself in their shoes. What would you like to receive in your email that would make you glad you signed up? Send them that stuff.
-When you do offer them something to buy, make sure it's awesome.

People get offers 24-7. Don't let yours be eh' just another mundane offer.

Stacey

Spend enough time to make it a good email. At the end of the day, you want to be putting out good and useful information. The more you do, the more reliable and trustworthy you will be, and that will help develop your following

When the people who follow you TRUST you and the information you give, then they will be more willing to help you out if you ask them for help, or better yet, genuinely check out a product you recommend.

In a nutshell, it will take a while and it will seem like people are just sticking around for free information. But if you give enough good information to gain their trust, they won't mind buying the rest of it.

It depends what you're emailing them about. If you're directing them straight to a sales page then I would put a lot more effort into your email than if you're just sending them to a blog post or something less sales. Because if you're wanting them to buy from you then you're going to want them well qualified before they hit the sales page.

Oh, and to give you an exact answer; I would take 3-4 hours to write a solid email that directs to a sales page.

You should take as long as it requires to get your email to where you want it to be. Even if you have to come back to it later. If you're not happy with it, chances are the customer won't be either.

Think of it this way: All of your subscribers have the potential to buy from you if you provide them with the right content. People are different, and have different "buy" triggers. Some will want you to be an authority on your product/industry (blog post). Others respond to out-and-out sales pitches (promos and sales letters). Yet others will want to see what other people think of your product (case studies and testimonials).

Mix it up. Don't rely on just one tactic to drive sales.

20 minutes. But I need to write it more often