Put a smile on your face. Sweet talking is a pleasurable activity, and you should show that you are enjoying it. Smiling makes you more approachable and it typically wins a smile in return.
Talk slightly softly. If you pitch your voice a little lower than you normally do, it encourages the guy to step closer. This creates a sense of intimacy and it shuts out other distractions.
Start talking about something that you have shared. Bring up a pleasant memory or chat about something that you have both wanted to do. Keep the conversation light.
Face the guy squarely. When you are creating an intimate environment, he should see that he has your full attention.
Touch yourself and touch him. Lightly touch your face or your shoulders, and if it is appropriate, reach out and touch him as well. The key is to bring him close.
Bring up what is in your mind, but do so jokingly. This is a good way to test the waters. If there is a serious topic under discussion, avoid sweet talk and bring it up in a straightforward fashion, but if you are just testing the waters, see how he reacts.
Compliment him and relate it to yourself. If you tell him he is strong, tell him how this has made your life easier or if he is smart, tell him what he has taught you or introduced you to.