From Ivybridge you could follow the River Erme upstream and head to the village of Harford, and from there access the moor at Harford Moor Gate. Then head north to Piles Copse, cross the river and proceed approximately north west to Stalldown Barrow, Yealm Steps, Shavercombe Head, Eylesbarrow Mine, Nun's Cross, South Hessary Tor & Princetown.
For the return route, head out of Princetown to Whiteworks, then skirt around the western edge of Foxtor Mires (take great care here - you don't want to head into the mire), then follow the green broken line on the OS map to pick up the Abbot's Way at Dry Lake Ford. (Note that this path is not always in existence on the ground). From Dry Lake Ford turn east along the Abbot's Way to arrive at an old disused railway track that comes down from Redlake. (This is known locally as the Puffing Billy Track). Follow this track (which also forms the Two Moors Way) as far as the point where the Two Moors Way leaves the track, then follow the Two Moors Way back to Ivybridge.
I hope this helps. It's not easy to describe the route but if you follow it on the OS 1:25,000 map you should be able to see it clearly.
EDIT: Bear in mind that not many inter-city trains stop at Ivybridge. You may have to change at Exeter.