- I'm not going to accept invitations from recruiters. Not just because I'm not looking for a job (who knows what the future holds?), but because I believe it shows a lack of respect to my network to bring recruiters one step closer to being able to contact them all. It's not about Evil or Good recruiters, but I really don't want to make it easier for lazy recruiters to spam people I respect (caveat: there are people who are technically recruiters who I have added into my network, either because I know them personally or because they have proved their worth).
- If I get an invite without an introduction message from someone who's name I don't immediately recognise, I'm going to check out that profile to see if we have employers in common or common connections, but usually I won't accept that invitation. I know LinkedIn makes it easy to click one button and request a connection, but I think my LinkedIn network is valuable and made up of people I know (even if I only met you once at a conference), and a short introduction reminding me of where I know you from (or why you'd like to connect) is going to help my poor, beleaguered memory.
- Endorsements - almost a total waste of time. People I have worked with and respect have accidentally endorsed me for things they know I've never worked on, simply because LinkedIn makes it too easy to click a button and endorse someone for two things they've already been endorsed for and a third thing which, through some LinkedIn magic algorithm, is probably related to what you've done before and LinkedIn hopes is only accidentally missing from your profile. If recommendations were too easy to game (and they were), endorsements are almost entirely valueless.
- It encourages you to keep your CV/resume reasonably up to date. I personally believe everyone should do this, not because you might want to hop jobs at a moment's notice (although it's nice to be able to do that), but because a) it's really difficult to remember what you did over the last 12 months, never mind a longer period - keeping your profile up to date means you can truly highlight the good stuff you've worked on, and b) if you've got nothing to add to your resume from the last 12 months, that's a good sign that you're not growing and your career needs a bit of love (if you think investing in your career is a Good Thing).
- It's enormously useful for retaining a network of valuable contacts. This is why, in my opinion, one needs to be reasonably selective about who one adds to that network. If you were looking for a new job, for example, and you'd been selective about the recruiters you'd added to your network, those would be the first ones you'd contact, and you'd be reasonably certain of a quality service. But regardless of that, because not everyone is constantly job-seeking, if you're looking for a specific person (for example, someone comes to interview for your company; or you're looking for a great speaker for your conference/event; or someone approaches you about a job or an event to go to; or someone randomly e-mails you out of the blue and you're not sure who they are) and they're either in your network or are connected to someone in your network, you know that you either know them or someone you know knows them. That makes them a Real Human and not a spam-bot or someone who wants something from you without giving value in return.
- It's not Facebook. Related to point 2, I am happy to add people I know only professionally (i.e. are not yet friends) to LinkedIn. I'm even happy to add people I don't know personally if they don't fall under rules 1 and 2 in the "I won't add you if..." section. In Facebook, I have two (main) rules: I have to have met you in person (there are one or two exceptions but those are people I have known for a long time only over the interwebs); I have to have spoken to you in the last year, or want to speak to you in the next 12 months. This is for two reasons: 1) I want to keep my Facebook network relatively small so it's more intimate, and therefore 2) I can share more personal things on there without feeling self conscious or wondering who's going to see it. I have to be able to speak honestly on Facebook. On LinkedIn, I don't need to be so fussy - I can add you to my network if I like you but you haven't (yet) crossed into friendship; I can add you if I think I can be useful to you, or you to me; I can add you if I want a way to contact you (or want you to be able to contact me) but don't have a pressing need to stay in touch frequently.
So, that's an unnecessarily deep dive into my attitude towards LinkedIn. It's probably not going to change anyone's behaviour, but I feel better for at least explaining why I won't necessarily add you back - all you need to do is type in the little invitation box to explain why we should be connected.
I value my connections, and I want to see that you do too.