Have you ever looked at one of those projects that had a super pretty appliqué design and thought that you would never be able to do this yourself? I felt the same way until i discovered how easy appliqué can be if you have the right tools - and it's really not that many.
I tried a bunch of different things before I found the easiest way to deal with almost any appliqué pattern. I discovered that Heat'n Bond is a big help when it comes to keeping your pattern in place before stitching it down. It's a light adhesive that you iron on the wrong side of your fabric before cutting out your pattern. I prefer the feather lite, since the stitching afterwards is going to provide the necessary durability.
First iron your fabric to the iron-on adhesive - do not pull off the paper yet. Then you draw the pattern - flower petals, hearts, you name it... - on the paper side of your fabric. Remember to draw it mirrored, since you are going to turn around the pattern after cutting it. Use sharp scissors, a rotary cutter or a cutting machine to cut out your pattern and pull off the paper.
Now you are ready to adhere the pattern. Place it on the fabric you want to adhere it to and iron it on with the right side up. Apply heat for about ten seconds and then let it cool down.
I prefer to use a blanket stitch to stitch down my patterns, but you can also use a tight zigzag or any other wide stitch that you like. Make sure that the stitches are close so your pattern does not fray. Just follow the edge of your pattern and you are done. Simple as that!
I especially love working with petals, because you can do so much with them by arranging them in different ways. I usually make my own templates with plastic sheets.