Next, consider what's going on with your body language. How close do you sit to one another? Do you turn your bodies towards each other? Are you often touching yourself (hair, lips, face)? The more you're facing each other and touching yourself, the more you're likely projecting what you want to happen - in other words, being close to them and touching.
Do you find yourself caring more about your appearance when you know you're going to see them? If you're making a point to wear your best clothes and use your favorite perfume or cologne when you know you're going to see your friend, chances are pretty good that you want to arouse their attraction. You should ask yourself whether you care about those things when you hang out with other platonic friends. If not, it's time to consider that your platonic friend isn't so platonic.
Keeping track of how you touch, use your bodies and present yourself is an easy way to determine what you really want from a relationship and puts you one step closer to knowing if you're more than just friends.
Once you've really nailed down your verbal and non-verbal communication habits, including body language, it's time to look at the reality of what types of relationships you both have with other people. All the signs might be there, but if your platonic friend is in a serious relationship with someone else or is sleeping with a lot of people, it might not matter.