By the time people go through all the various "setups" recommended I've had my rifle bedded and have been shooting for two or three days.
Just remember, if there is already a pair of pillars installed, the stock is inletted for the bottom metal, or some combination thereof, where and how you are going to mount and bed the action/barrel is already pre-determined.
If you're starting with an "empty stock", no pillars, no action block, just lots of room for bedding compound, then maybe farting around with levels, etc, might make sense.
But if you can't relocate the bottom metal and thus the screw holes, that's where you have to build from.
Some of the best jobs I've seen involve nothing more than a big O-ring around the front of the barrel where it meets the front of the stock (after check fitting to see that there is plenty of clearance), a piece of tape under the last 1/4" of the tang, and then just bedding the whole mess, making sure that the ejection port lines up and the action screws are finger tight in the botom metal. If there are no pillars in the stock yet, get a set and fit them to the action, bottom metal, and stock before bedding. Then Bed the entire assembly at the same time. Use some stock fitting pins instead of action screws and hold the pillars in place by either wrapping the pins with tape or use o-rings that keep the pillars centered on the pins. When you have it all cured, after wrapping bottom metal, action, etc with surgical tubing or elastic banding, when the pins are removed the action screws will be dead center to the pillars with no chance of contact under recoil or heat expansion.
For pins just take some 1/4" rod stock and get an inexpensive 1/4" X 28 die to cut threads on one end.