In the more informal services at my church, the worship leader is usually the one who invites people to stand at the beginning of the service. In other churches or in more formal services, either the church’s pastor will do this, or the first hymn will just start and signal that everyone should probably stand up.
I’ve seen worship leaders invite their congregations to stand in some pretty funny ways.
Some are timid or nervous and don’t quite know what to say. They might say something like “uh, hi everyone, please find your seat, uh, please stand up, and please, uh let’s sing this first song ‘How Great is Our God’”.
Well, if you say so.
Some are overconfident and come across like they had a bit too much coffee to drink. “Hello everybody! I said hello everybody! Alright, that sounds more like it. Now let’s stand to our feet and worship the Lord! I said let’s stand to our feet and worship the Lord! Are you with me? Yeah! One, two, three, four!”
I think I might have a headache.
Others just say random things like “get on up!” (reminds me of a James Brown song) or “please rise” (reminds me of a legal proceeding).
When it comes to the very first thing a worship leader says in an entire service, it’s important that they not come across as nervous, annoyingly enthusiastic, flippant, or robotic.
Just relax, make eye contact, and say something simple like “good morning everyone, why don’t we stand together and sing to the Lord”. It’s confident, simple, and clear. Or “let’s stand together this morning and proclaim God’s glory as we sing”. It doesn’t need to be fancy or eloquent. It shouldn’t be more than a sentence or two.
It’s not the most difficult thing in the world – and it may come easily to many worship leaders – but it’s easy to overlook until you get onto the platform on Sunday morning. Just treat your congregation like your family and kindly invite them to stand. An awkward start is just plain awkward. A smooth start makes things easier.
Oftentimes at my church we’ll start playing a few measures of the opening song, and then I’ll ask the congregation to stand before we start singing. Here’s an example of how I did that a few months ago before singing “Praise the Lord” by Bob Kauflin and Doug Plank from Sovereign Grace Music (it’s on their Psalms CD). You’ll hear people chattering at first, and even a bit during the first verse, but slowly people join in, and by the chorus we’re all singing together.
Worthily Magnify 
Why do worship leaders ask people to stand. I am more comfortable and relaxed and feel the music more of i am sitting during worship. I feel an obligation to stand when my hart doesn’t want to. My church didn’t used to do it and people just stood if they wanted. That was cool. Being asked feels like you are doing something wrong if you don’t. I just don’t understand why it is asked. Why not let the people worship as they want. I know they can but I’m just saying how i feel and i know others feel the same.