This is the heart I use. Find one that works well for you. I found that this one works better than trying to use a fancy heart.
I'm using the font Impact at size 144 to start. You can use other fonts, but I found this one easiest to get started with. After you've typed your word, ungroup all the letters. Do not release compound path as this will make the middles of your letters ungroup as well. Using ungroup will just ungroup the letters from each other.
Manipulate all the letters so they overlap the heart. I use the corner stretching and the top/bottom and side stretching. This takes a little adjusting. Don't worry about making sure all points over lap the heart at this time, we'll fix that next.
Duplicate your heart. Now you have the extra one and the one around your word.
Highlight your word and your original heart and then select crop from your modify tool box. You should get something that resembles the above picture. Then line up your duplicated heart so it lines up flush with the crop (I forgot to take a screen shot of this step).
Now zoom into your image and work through your letters. Double click on them so you are able to manipulate the points. Pull each letters points so they are flush with the heart. Like in the next picture.
I actually pull my points just past the heart and you'll see why in a second.
Okay, now you've got a big ol' mess that looks like this. I've also duplicated my heart again, just in case. You're going to highlight it all again and hit crop again.
And that's it. If you need to, you can drag your heart over and play with the points again to get the look you want. Like I said, if you have any questions, please message me. I hope this tutorial was easy to follow.
And if you're coming here looking to just purchase this done in vinyl, visit my facebook.