I used to drive the big red London buses, and carried a Public Service Vehicle Licence for manual / standard shift coach and tow up to 75 feet combined length for 24 years.
Start without the tow.
Go find yourself an empty parking lot, and get used to some low speed maneuvers.
Your main difference between a large RV and car or a truck, is that the steering road wheels are behind your ass is a class A or a Bus style RV, in a class C you can drive it as a large fixed chassis truck.
Find a comfortable position on the road, this will need some retraining, you can check behind with either mirror or rear camera, you'll need to be about a foot to a foot and a half further left, than will feel comfortable to start off with, due to the width of the vehicle.
You can actually move nearly another foot to the left and still be safer yet as it will keep you off the curb.
Take your position and adjust the seat front to back, up and down and tilt so your heels can rest on the floor, and you feel natural, (or as natural as you can be when thinking about the size of the vehicle), have the mirrors adjusted so you can see some of the side and back end of the vehicle in each mirror, if it has 2 part mirrors, have the lower part set a little wider to give some coverage of your blind spots for passing.
Have the people you're buying it from give you a walk through on all the buttons and dash / driving controls, main dealers often provide a quick class on other RV features, it takes an hour and most that I have seen like to charge a $100 or so for something that I for one, think should be part of the service provided when spending $1,000's on an RV.
Once out on the road, sit as near the lane markers on the drivers side, as you feel comfortable with, you can see them in your mirror and anywhere between a foot and a foot and a half will be a good place to start out.
If this is your first time driving on the right hand side of the road, ask the salesman for a set of left turn instructions around a block that is near their depot, the left turn is easier to master than the right on a class A in the US, if you can do it on wider streets with traffic lights that helps too.
Position yourself, (and the RV), in the turn lane, if there are two turn lanes, pick the right hand, (left turn lane), when the lights change to green, pull straight ahead for 4 or 5 seconds, then begin to make the turn, with the wheels behind your a$$ in a class A, you actually need to move forward before you turn, or you will cut the corner with the side of the RV, and crush any car in your blind spot.
Repeat the same procedure another 3 times and you are back on the first road you drove on.
A lot of the road markings give you a pretty good line but always remember to drive forward before you begin to turn the steering wheel in a class A, if you are driving a class C, it is so similar to driving a car or a large truck, that it feels quite natural to a proficient driver.
Keep some attention to what is happening to the back end of the RV as it moves in the opposite direction, swinging out to the right as you make those left turns.
On right turns, set up as far to the left of the right turn lane as you can, when the lights change pull forward, as far as you can before you start to make the turn, on standard US city streets, there is plenty or room to make these maneuvers, don't actually start to turn until your back wheel is at the corner of the curb for the corner, (your initial move forward should be slow and steady), slowly begin the turn, pay some attention to the curb and the corner, but also keep some attention to the drivers side back end of the bus drifting left as the front end moves right.
Once you have done a couple of blocks of left and right turns, and practiced with the brakes, part of braking that makes things smother the more you practice with it, is the lift, even under hard braking, the last part of coming to a halt, involves coming off the brake peddle a little, 35 - 40%, this allows the front end of the RV to lift before you stop, if you learn this braking trick it stops, or at least reduces some of the bounce that can otherwise occur.
Driving with a tow at around town speeds, means driving ahead just an extra second on left turns, and allowing your back wheel to just pass the curb on a right hand corner, that small amount of extra time allows the hitch part of the tow to pass the turn easily, and most of the time you wont even notice the tow is there, as long as it is set up properly, and the brakes on the tow have been set up well.
I tow light trailers so I hope someone that uses a Toad will give you a better run down on that part.
The other thing that it helps to remember is that unlike the car driver, who may look 100 yards ahead, (if he or she is a good driver), you need to be looking 250 - 300 yards ahead, and the nice high driving position allows you to do that.
Look well ahead and adjust your speed accordingly.
When on the street or highway and moving at speeds above 45 mph, keep your eyes ahead and scan your mirrors or rear camera every 15 - 20 seconds, pay attention to vehicles that are moving from visible in your mirrors a long way back, to getting into the blind spots alongside you RV, if you know what was there or was about to be there, you have a much better grasp of what is happening around you and be a safer driver for it. Part of this part of driving is your lane positioning, you can add either tape to the top of your dash or pick a mark of chip on your windscreen, that relates to the position of the road markings ahead of you. I have a 93 Friendship, and the is a convenient, (for me), rock chip, shaped like a J in my eye line at about 50 yards in front of the RV, as long as the J and the left hand lane markings line up, I am positioned the the center of an 11' or 12' American lanes.
For my driver training on London Transport, I was paired with another trainee and an instructor, and it took me 9 days training before I took my test, half the day you were driving and half the other trainee was driving, to start you got 45 - 50 minutes driving, then the same as a passenger, the times increased to two - three hours at a time. Shifts once working were limited to 4.5 hours driving per half of a shift, and if you exceeded 5.5 hours on the first half of a shift due to road conditions etc. you did not need to complete the second half of your shift, unless you chose to do so as overtime.
I used to drive a VanHool 50' deck and a half, (76 seat), charter coach, and tow a 20' luggage trailer on the European roads, so I was conversant with driving on the right with a large vehicle, but I didn't do that until I had 6 years of bus and coach work under my belt, the extra length is mostly just adding more time in the turns for the longer overhang of the front and back of the bus to allow it to pass the road you want to take, and then to turn into that road.
While driving on the continent you could do 9 out of 24 or 14 out of 36 running with two drivers, which made most places accessible in the 28 hours driving that two drivers could put together, London UK to Saltzburg Austria was an easy run, and even to the port of Brindisi in Italy was possible from a start in London, over 1400 miles in about 25 hours drive, that was the most economical route to Greece as it allowed drivers to comply with driving / non-driving regulations as the ferry ride counted as non-driving but still as paid work.
I drove over 1.25 million miles in 22 years of commercial / coaching work, sounds like a lot, but it really only averaged out at 260 miles a working day of driving.
If any part of my description doesn't read clearly, please feel free to PM or email me and ask for clarification of my terminology!
