I've hitched in about half of the states in the US, and I went to many of the states multiple times. I've had both good rides and bad ones. You probably will too. You already know the risks you are taking so I won't say any more about that.
I still pick up hitch hikers but I don't pick up anyone with baggage or more than one person. You will have a tough time getting rides. It will be extremely hard if you choose a male for a traveling companion.
Only take what you have to and use zip lock bags in case you get caught in the rain. Don't take a check book or debit card. Good shoes are a must. You'll be doing a lot of walking. It is illegal to walk on interstate highways--so don't try it. You WILL get caught. Some states allow hitch hiking and others don't.
I always hitched rides with semi's. The reasoning is because they have a reason to be on the road. Most drivers are just normal working folks. I went from truck stop to truck stop. The disadvantage is that most of them carry guns in their rigs and the cab is pretty much sound proof. Still, I always thought it was safer than hitching with cars since you never really know why they're on the road.
Good luck. You have taken a course in self defense, haven't you?
