There is one that I use for putting, but can be adapted for the full swing using a Metronome.

Set the tempo rating to 120. That is 1 tick per 1/2 second. Then start swinging without listining to the ticks...just go through your regular setup and shots. Do this for about 10-15 balls.

You will naturally have listened to the beats and will have a good idea if you need to speed up or slow down the tempo. So, make a guess at the next speed you want to set it at. What you are looking for is to have the start of the swing to the top be 2 ticks, and then have impact be the third tick.

The putting drill is with 1 tick back and one tick through.

Don't play with this metronome for more then 20 balls. You have to turn it off for 2x more times then you practiced with it. Otherwise you get too acostomed to it and that is all you think about. You have to be able to train you head to have it's own clock. Your optium clock is not always a perfect ratio of ticks, it could really be 1.657943 to 1 and not the 2 to 1 in this drill. But what this will allow you to do is know if you are ahead in the count on the takeaway or slow on it. That is really where tempo is lost, on the takeaway. You get really slow and then jerk from the top, or you take it back fast and have to decelerate through. You want a simple, uniform and repeatable tempo each time.