Having kittens, not literally!

If someone could help here I would be eternally grateful.

Briefly, I am freelancing, doing a bit of work on the side of my day job. At the moment I am designing wedding/christening invitations.

I have come up with a design which I am printing from home using a Canon Pixma mg5550.

I am using Illustrator to create the invites and have chosen the colours. On the screen they are perfect, but when printing they are way off. I have tried everything. i have calibrated the monitor, assigned colour profiles and it still isn't doing the trick. The way I am getting around it is knocking up my own swatches on an A4 piece of paper and changing the colours/printing them over and over again to get them to match what is on the screen.

For example, for one colour I was a sort of dark jade green, when printed this colour comes out like a sort of racing car green and much darker.

If anyone can give me some advice on how I can pick colours and get them to print the same I would very much appreciate it.

Many thanks

Thanks for the reply. I am working in RGB as I read you get the best results this way. I am also used Adobe RGB 1998 as the colour profile. I did convert it to CMYK to see what it would look like but it was even worse. I know the printer can print the colours I want as when I keep changing the shade in illustrator and printing over and over as trial and error, i can get there eventually but it looks completely different on the screen and doing it this way takes hours.

Thanks again.
First up the Canon Pixma mg5550 is a 5 colour printer so you should be working in CMYK.

When you say you've calibrated your screen, what have you done? bought a colour calibration tool such as this: Amazon.com : Pantone huey MEU101 : Computer Monitor Accessories : Electronics, or did you just do the built in calibration on your computer? If its the latter you're not really calibrating anything other than how you think the screen should look.

What paper stock are you printing on?