If you set to the smallest aperture (I use a macro lens that goes to f32 or something crazy like that!) and manually set focus to closest distance, then point at blue sky, then look at the image you'll fall off your chair. It's actually quite horrible to see just how dusty the sensor gets when you "encourage" it to show it's true colours to you with those settings.
Everyone has their own opinions on this and different things work for different people. I've been cleaning my own sensor for many years and I still dread it every time. The only way I've ever managed to get a clean sensor is by using wet swabs (Digipad or similar, so basically a pec-pad wrapped around a plastic spatula). Put JUST ONE DROP of Eclipse 2 fluid on one side of it before cleaning, otherwise you will leave behind a streak that will only come off with more wet cleaning. Wipe the sensor's protective glass one way, then the other, using the side with the drop on. Then turn it over and do the same with the other side to help dry off any leftover streaking. Take another test shot and see how it looks. Expect to see some dust still, and don't keep cleaning or using more and more fluid, or you'll end up worse off.
I would never send a camera off for cleaning, as they'll only do the same as you can. They don't have any sort of powers to do an extra good clean, and I've read many stories of sensors coming back with even more dust on.
The last attempt I made at sensor cleaning was to buy one of those loupe things, like a small magnifying glass, that you place over the camera. They are backlit and magnify just enough so you can see dust specs on the sensor. You can then clean it, and take another look, target the leftover specs, look again, etc.. It FEELS wrong to do it that way, but twice now I've found it far quicker and less stressful.
You'll never be able to get rid of all the dust, and if you do, it'll be back the next day. If you often look for it, you WILL find it and it'll drive you crazy. What I do now is carry on using my camera, and if I get to the point of seeing dust regularly and it's making processing difficult, then I give it a clean. If you want to remain sane, just don't do that test to look for dust unless you're in the process of cleaning. Also if you're cleaning and you're left with 10 dust spots scattered across the sensor, LEAVE IT ALONE.
I know some people claim to be capable of cleaning every spec of dust off, but if they do a thorough test I think they'll be shocked just how dirty it still is. In the real world though, you'll never notice. Having OCD tendencies, as I do, is not great when it comes to sensor-dust!