This really covers many aspects of marketing. The first step to generating a online lead is getting them to your website. Organic SEO is the free way people find you on the web. However, there are a lot of instances where organic SEO isn't enough. Some of those factors would be age of your domain, competition and website content. When this happens, you must advertise your website and products/services through other digital channels.
Google Pay-Per-Click
Google PPC are the ads that appear at the top of search results with the little green box that says ad.
Weather you should use PPC highly depends on your industry and competitors. If you have a national audience that is highly competitive, then PPC will be a costly way to drive traffic to your website. Good thing for you is there are alternative options. If your customers are local or regional, Google allows you to drill down your geographical target area which means you will get more bang for your buck.
The other thing you need to know is that click-through-rates (CTR) on paid ads are below 20%. People tend to skip paid ads and go to the first couple of organic results. Bottom-line, build a quality website with good content optimized for SEO and you won't have to pay for your traffic.
Social Media
Not having a social presence is no longer an option for small to mid-sized businesses. There are too many people using these networks to ignore this marketing channel. Using Facebook, Twitter, LinkedIn, Instagram and now Snapchat seems like an overwhelming task. The good news for you is you're right. You need to identify 1-2 social media networks that work for you company and stick with them. For example, if you are a B2C (business-to-consumer), your focus needs to be more on Facebook and Twitter. If you are a B2B (business-to-business), LinkedIn should definitely be a part of your strategy. This doesn't mean you can ignore the others. An ideal approach is to try 3-4 of these and evaluate where you are getting the most qualified leads.
In addition, placing ads on social media has drastically improved over the years. You now have the ability to drill down to your target audience giving your business betters odds of displaying ads to people that are actually interested in what you offer. For local B2C companies, Facebook has become a cost-effective way to drive traffic to your website.
For example, if you are a plumber or electrician that provides services within a 30 mile radius of your location, wouldn't you like to promote your business to the people living within those 30 miles? And then only pay for those ads when someone actually clicks on it and goes to your website? If you're not sure, the answer is yes. That means you will appear in their feed the rest of the time for free. What a great way to build your brand and awareness.