The original purpose of this thread is to get the OP started with his printing. But going down the track he will eventually come to where you're at.
Originally Posted by DannL
As others have said, the benefit of making test (strips) with log changes (2,4,8,16, ...) is so that there is equal difference in exposure between the tests. You work in the same way as with your camera.
So, for starters, making a test strip in full stop decrements is a start. Then when in the ballpark, i.e. somewhere at an exposure time or in between two of them, you can finetune in increasingly smaller decrements.
As someone notes, there are programmable exposure timers, with which you work with the concept of stops instead of seconds. These timers (R H Design and Darkroom Automation.) can be set down to 1/24 of a stop, which should befine-grained enough. (If you miss your half-second, you can always let your hand pass under the lens...)