i was/am a pro motorsports photographer (mainly bikes) so cant offer much help as the shutter speeds, apertures and ISO's are completely different to say...landscape and portrait.
What i used to do when i first started was shoot say 5 or 6 shots using a certain setting, write down the setting in a little notebook then change said setting either 1 click up or down and take 5 or 6 more, write that down then carry on the process.
When you upload them to your pc you can then tell if they're too dark or whatever and work it out from there