I use the right hand rule

https://en.wikipedia.org/wiki/File:Right-hand_grip_rule.svg

Point your right thumb in the direction you want the screw to go, and your fingers will curl in the direction you need to spin it.

If you accelerate to a very high orbit, you will have nearly zero velocity at the apoapsis. From there it takes only a very small delta v to reduce your velocity to zero and fall into the sun.

Source: This is how I killed Jebidiah Kerman.