This entire post from Scott Stratten (The 5 Ways You Suck at Linkedin) is completely on point, but this item really resonated with me (I've posted about lazy connection requests before):

Twitter + LinkedIn = Litter – Go login now to LI and tell me what you see from people and their “status”. 98% of what I see are automated feeds from Twitter. Broken @ names, and “via Twitter” all over the place. Is that the message you want to send to your business contacts? That you’re not there but you’re giving them the honor of reading your tweets? Social media isn’t about being everywhere, it’s about being great at where you are. Stop the social synching.

Don't be that guy

So, so true. It's important to remember, too, that some people -- maybe even many people -- follow you on more than one channel. At least do us the favor of switching up the language and ditching the hashtags and @s. Make it seem like you're at least trying.

Yeah, I know you're incredibly busy. But just because apps enable you to post to the same sites at one time doesn't mean you should abuse the privilege. You've got two minutes to devote to writing different versions, at least, of your updates. Maybe even scheduling different days for each network. Anything to show that you're doing more than the minimum.