cf apps
I usually start with this as now I get the AppName for cut-n-paste and if verifies I am where I want to be in space and cloud. And yes, I really really want to say space and time.
cf rs AppName
cf logs AppName
cf logs AppName --recent
Note, depending on who is hosting your CF app, the size of this log may be limited.
CF keeps you logged in. I sometimes have to switch between regions and don't always know where I am #Where am I?
cf target
#Login. This is logging in to the UK region of bluemix. Replace eu-gb with ng to go to the US.
cf login -a https://api.eu-gb.bluemix.net
#List spaces
cf spaces
#Change space
cf target -s OtherSpace
#Change organisation - for when someone adds you to their org usually. This will normally have to be followed by a target of the relevant space.
cf target -o OtherOrg
cf ssh AppName
Only for Diego apps. Useful to see what is actually running.