Hiking route I would suggest
It seems to me that the east side of the lake has more attractive scenes for me, such as the Balanced Rock and Devil's Doorway, and not to mention you can get a good view of the whole area.
You can either start from the east bluff trail or the balanced rock trail. However, I would suggest starting from the balanced rock trail as this is a difficult and steep and slipery rock step trail - it is easier to go up instead of going down from there. If you go up from there, it would be a lot easier to come down from the east bluff trail since it is not steep at all there.
Equipment: Make sure you get enough water with you as you can't find any drinking fountain on the way up, not to mention vending machine...
Hiking on the rock steps is not easy - don't try to bring too much with you. Make sure you wear the right shoes as the rock steps are slipery.
There are several guide books to this area. You can find them at local sports stores. The East and West Bluffs are where the majority of climbs are. Climbing Magazine also had an article about this area in one of the 2000 issues (or was that 2001?).
Equipment: If you can't gear climb, you must be prepared to top rope. There is NO (read that - NO) bolting allowed at Devil's Lake. It is easy to set up top ropes here - be sure you have some very long webbing. You can sling boulders the size of VWs to protect your climb, or put some stoppers (nuts) into cracks at the tops of the cliffs to set up your anchor. Be sure to set up a minimum of 3 anchor points, and use an equalized knot. If you don't know what this means, climb with someone who can show you - results of inexperience here lead to injury or death.
Don't forget your camera when you hike
There are so many great scenes on the way to the top. I bet you would regret if you forget your camera.