I love this topic! My office job is doing social media and I'm pretty passionate about it, for non-profit & small businesses, since that's what I do and it's so cost-effective. There are of course a lot of commonalities for "vanilla" and camming social media, but I find its harder when you can't just be like "here's my boobs!!!", lol.
For example hashtags, camgirls use a ton and I find it super useful with camming, but more than two on a business tweet looks tacky & spammy. (Also if you're doing Tumblr, important to know that it's the first five tags that count for searches, so you don't need to use a ton of them unless you're using them to track yourself! I only use tumblr for camming though so I'm not as familiar with it as other girls are!)
Anyway I think it sounds so cheesy and buzzword-y, but it's so important when you're starting out that you don't come across like you're selling something (even if you are). The most effective tweeters are offering more than they're asking for. Whatever industry you're in, I find posting links to articles or resources related to it is a good way to offer something useful and give people a reason to follow/retweet/engage you. Especially if you can while you're developing the project, it helps build up followers and interest.
I'd also say developing a voice that's relatively casual (while still professional, of course) is helpful. Sounding like a real person as opposed to a Tweetbot, you know? An anecdote: recently my friend tweeted about a comic. Someone who was writing a different comic saw the tweet and replied to her, essentially pitching their own comic, BUT they did it in a personal, funny way. She not only followed them, but she also told me about it (word of mouth!), and preordered the book. People send spammy "buy my shit" tweets all the time, but theirs was personal and funny, AND they targeted it towards someone who expressed interest in something related.
At work I will go through follower lists of similar companies and look for people who seem interested in what we do. If I think they'd actually be interested or benefit from it, I'll follow them or send a tweet. Personally I've found being proactive helps, as long as you go about it in a ~genuine ~ way and aren't being spammy. I just try to send tweets that wouldn't feel invasive if someone sent them to me.
But yeah, id follow industry folk, potential customers, people who might talk about your business and influence others, etc.
I'm super against linking your accounts together, generally. It's pretty easy to just type out your own tweet and include a link to your Facebook post, for example, but you can make sure the words don't cut off in a weird place. I think it's worth the time to create individual posts for each network. (Side note: can't even count how many camgirls I've muted or unfollowed because their Tumblr links to their twitter and they reblog like 100 posts a day. Obviously it's no loss for them if I unfollow, but worth considering how it appears to potential members.)
Other stuff - posts with links get retweeted something like 86% more often than tweets without, tweets with photos are like 94% more likely. So when appropriate, use those.
Depending on your industry, LinkedIn can be super useful too. If you're just starting up it could be a good place to network with people who could help or boost your brand.
Try to respond to your followers super quickly, and if someone rerweets or reblogs you, or posts about your business, I think it's nice to send a thank you.
Again it's totally dependent on what you are doing and where you want to focus but those are a few of the things that have worked for me at the places I work at! Twitter, Facebook & blogging have been my most-used networks and twitter is definitely my favourite for networking & engaging customers. Instagram is fun too if it fits your business!
Also, set measurable goals so you know if it's working. Most companies I've worked with don't do this, it's batty! Whether it's gaining followers, getting reblogs, selling products, etc, just something you can use to see how you're doing. (Sorry if any of this is obvious, I'm just kind of brain-dumping)