I have been in PR for close to 20 years and placed clients in NY Times, CNN, Conde Naste publications and major outlets around the world. To answer your questions:

-Would email or phone call be better?
Email as a first point of contact. Keep your message to under 200 words and your subject line direct and short 45-65 characters long max.

-How do I get their phone numbers?
Ask for their number in your email. Alternatively every media outlet has a masthead with names of writers and editors and sometimes a number for the office. Call the main line and ask for the extensions of the people you want to connect with.
- If I send an email would it be enough to simply say "Hi....this is my exciting new site and it does xyz, I thought you may be interested in covering it. Please let me know if you want extra info."?

Your company launching is not news. What you need to do is discover the story angles for your company and website. We call it the 'story hunt.' Bloggers and journalists are not there to promote you or write about you. They are in the business of 'news' and also serving their audience and looking for timely subjects that will get them the most clicks and are shareable. To do this right you need to think like a journalist and ask yourself is it really newsworthy?
Are you:

The First
Controversial
New
Broken
Unique
Scandalous
Unusual
Provocative
Better
Corrupt
Problem Solving
Problem creating
Innovative
Scam
Faster
Conflict

If you fall into one of these categories they will likely consider you newsworthy. You want to be newsworthy for the right reasons so keep that in mind.

-Do I help them craft an interesting angle to the story?
Yes 100% it's your job to craft the story and come up with angles and supporting evidence for that angle.
Here is a post we wrote about how to help create an angle that they would bite on.
. Provide a twist on trending news.
If a particular trend, style or accessory is hot in the media, you can bet that journalists are scrambling to one-up each other with new stories. You can fill that void — but you absolutely, positively must show up with a twist to the story they’re already reporting. Share a personal story, a surprising survey result or the contrarian view.
2. Localize a national story.
Pick up your local newspaper or flick on your local breakfast television show, and you’ll see countless examples of businesses that got their 15 minutes by being the local example of a larger story. These types of stories are the bread-and-butter of your hometown press.
3. Nationalize a local story.
This trick also works in reverse. Scan your local news for hometown stories and ask yourself, Does this story have national relevance? How can I frame it for a reporter, and insert myself in the story in the process? This is how a lot of freelance writers get their ideas — and it can work wonders for you, too.
4. Be a contrarian.
Objective journalism hinges on getting “both sides of the story.” If you’re seeing a one-sided media conversation about a trend or your specific product, it’s an opportunity for you to break through as an expert — especially if you’re willing to champion the underdog opinion. Once upon a time, no one believed anyone would buy luxury fashion online. Net-A-Porter, a now multi-million dollar business, categorically proved them wrong.
5. Personalize big data.
Very few micro businesses have the data samples or poll results that attract press. But that doesn’t mean you can’t be the case study that helps the reporter tell the data story. Set up alerts for surveys and polls on topics relevant to your business, and let the media know when you’re the case study for the results (or the exception to the rule).
6. Reinvent the holiday story.
Sick of reading the same-old holiday or seasonal stories? Journalists are tired of them, too. And, yet, it’s inevitable. Every Mother’s Day, you’re going to read countless stories on gifts for mom. If you can give a reporter a new spin on that seasonal feature she has to write every year, you’re on the fast-track to being her go-to source when she’s writing a story on a deadline.
7. Are you releasing something new? Use it!

-Do I show them how it ties in with previous stories?
Yes if it does show them definitely.
-Do I try to send pics, a link to the site, interesting infographics or attached pdfs about site?
Your first email will be short and direct with no attachments and no fuss. When they reply saying they want more send them all the goods and make sure you tell them that you have all the goods in the first email.
-Do I ask them straight out to cover the story or do I tell them their readers may find value in our offering?
Asks should always be direct. Don't waste people's time. However the idea is you have a story angle that is VALUABLE to them and to their readers. Their audience has to find value in the offering. Without that you are just asking for promotion in exchange for nothing. Always ask yourself, 'what's in it for the journalist?' before you fire off a pitch.
-How do I ensure they don't just read the first line and delete?

Make the story compelling! If you know the journalist ( a must!), know what they write about, know their beat, understand their tastes (hint: follow them in Twitter) and you've sent them a good targeted, personalized pitch with a strong hook they are less likely to delete after the first line. You need to be a good listener before pitching journalists and understand the anatomy of a good story. Good luck!
If you want more tips and trade secrets happy to chat with you. Our agency doesn't take no for an answer and we have a reputation for being tenacious and getting a crazy awesome response rate because we take the time and invest in listening to the press so we can be of value to them. You got this!