I've lead the marketing team for 3 VC funded startups that all successfully acquired customers en mass, but along the way I've certainly observed a fair share of startups that failed due to inability to acquire customers fast enough. Here are some common reasons startups fail:

1. They incorrectly think their product is so good that the customers will just show up and pay
2. The product is "cool" but doesn't solve a pain that valued in the market
3. Users like the tool enough to beta it for free but not enough to actually pay for it
4. Company acquires customers but the lifetime value to customer acquisition cost isn't sustainable, or requires such scale that the company never gets there
5. Most companies waste a ton of money on Adwords until they realize they should hire an expert
6. Startups acquire traffic but can't convert it into repeat purchases or usage
7. The market just isn't big enough
8. There's another solution that is more compelling

There's a ton of other reasons too. If you're having trouble acquiring customers, feel free to give me a ring. Happy to chat any time.

The best way to do SEO without paying someone else is to teach yourself how to do the basics. FIrst, you should read several resources about SEO such as: http://moz.com/beginners-guide-to-seo Then, you should use a few free tools such as http://marketing.grader.com/ and http://raventools.com/ (Free for 30 Days) to audit your existing site. Then, implement everything you learned and fix everything the tools say is broken. Keep working at it until you rank #1 or aren't sure what else you have left to do.

Ultimately, you get what you pay for with SEO. You can certainly teach yourself the basics, but if you want to compete in a competitive market then hiring a real expert may be worthwhile once you've done what you can on your own.

Here is how I'd suggest you learn SEM:

#1 - Open a Google Adwords Account (You can search for free credit / promo codes) online and play around with it.

#2 - Review all of Google's training material: https://support.google.com/adwords/?hl=en&page=examstudy.cs#topic=3119071

#3 - When you finish Google's training materials, then read about Adwords on the web. Here is one good resource and you can Google for more:

http://www.wordstream.com/adwords-for-dummies

#4 - Sign up for an affiliate network (e.g. Commission Junction or Linkshare) and use your free credit to promote another company's offer.

#5 - Once you feel comfortable with Adwords, consider building out your own Lead Gen websites or selling leads to existing affiliate networks (e.g. Motive Interactive or Integrate.com)

#6 - If you'd like to learn from someone else, find an entry-level job at an agency: http://www.indeed.com/q-PPC-entry-level-jobs.html

#7 - Another good way to get good at PPC if you work in an in-house marketing role is to hire someone to audit or manage your own account for a period of time so you can learn how they think and what they do.

#8 - One word of caution: Google takes a minute to learn and a lifetime to master. Their default settings make it very easy to waste a lot of money so really make sure you know what you are doing before you spend too much money.