What is the best way to start SM ?

Social media is free: Not really. It may be free to create a profile on each social media channel, but it takes a lot of time and well-directed efforts to be successful. And who knows the importance of time more than a small business with limited resources? Therefore, while it is important to be on social media, it is even more critical to have a practical plan grounded in reality — a plan that takes into account the time you can spend on social media, the kind of campaigns you can run, the money you can invest, etc.

Before starting SMM you need to create interesting Social media profiles to attract followers, follow a specific theme of your business, share informative and attractive post , you should follow people who are related your business.

One good place to start is simply to dive in on the top platforms like Facebook, Google+, Twitter, Pinterest and then spread out from there. There's tons more communities that I can list but you shouldn't overwhelm yourself joiningg every social community under the sun. Just start and test a few to see which works best for you to find and connect with your targeted audience. No use in trying to mix with communities who don't stand a chance of being receptive to what you have to offer. Yes, you shouldn't flat-out sell while doing social marketing (you have to be more relaxed and socialize in order to attract people to your offers) -- but at the end of the day it's not just about socializing, you have to see a return on your time and investment spent doing social media marketing. Hanging out all day shooting the breeze on social platforms and seeing no return SUCKS! So before starting social marketing campaigns be sure to know exactly what you need to achieve from it for it to be worthwhile for you.

Social media marketing is not as easy for you to see results. You need to dedicate your time to do some hard work, by giving more valuable info to your friends, fans or followers. First, you really need to attract them with your own social media profile. For example, if you are into Twitter, you definitely need to put out your effort to be creative in building your own profile. Make it complete and realistic to your own followers. The same thing goes to the other social media sites.

In the end, once they are so attracted to your own Twitter profile and giving valuable tweets, they will start following you, and might recommend others to follow you as well.

test often. fail often. learn quickly.

Start with LinkedIn.

Well there is nothing overly complicated or exclusive about Social media and you certainly don't need to "learn" it, just make sure you are engaging with the users and not just about publishing regular content or likes/followers.

Take a quick read of the 2013 Social Media Marketing Industry Report (free immediate access). It is full of valuable information and includes answers to important questions such as, “How much time does social media marketing take?,” “What are the benefits?” and “Where are marketers focusing their energy?”

Best thing to get succeed with social media is not to focus on one or two medium initially, dont jump into many as it will not be easy.
If you are concentrating on one or two initially, then you will be learning more and more and will be implementing new strategies there.