1. Pick an airframe that is big, slow and self-stabilizing - helps avoid mistakes, gives time to correct, assist with correction when needed.
2. Do your best to build the plane straight, especially if you don't have anyone to do the maiden flight and trim the plane out for you. There is nothing worse than trying to learn how to fly "straight" when the plane does not do that by itself.
3. Build and fly as light as possible to minimize consequences. That includes using reasonable glue (instead of hot glue, which is heavy) if you can. Build the bare minimum - no accessories like landing gear or anything, as few servos as you can get away with etc.. Try to use the smallest battery you can (e.g. to get the CG correct) - as a first timer, your flight times will be short anyway.
4. Use rubber bands to join parts wherever possible (fuselage with wings, etc) - that helps to dissipate the energy of a crash.
5. Fly only in the perfectly calm weather. For the first 10-20 flights, don't even think about flying in any other conditions.
6. Use the lowest control surface deflections recommended. If you are going to do 5, go even lower than recomended, especially on the elevator. This helps with avoiding pilot-induced oscillations and general loss of orientation.
7. Shallow turns. Preferably below 15 degrees, never exceeding 30 - especially when the plane is flying towards you. That helps keep the orientation and gives time to observe and correct.
8. Most crashes happen on take-off and landing - be patient to learn those properly. More on that later.
9. Try not to fly too far or too high - the farther the plane goes, the more difficult is to see what's going on. And this happens way closer than you think.
10. And do not "panic" - if you get into trouble, just "drop everything" (all controls to neutral, zero power). When you are at the beginning of your journey and make a serious mistake, you are most likely going to make it worse, not better. If you do points 1-3 correctly, your best bet most of the time is to let the plane handle your mistakes itself.
Now, I casted a vote for the Storch - in my opinion it is the best plane ever to learn. But to be honest, I was never 100% "fresh", and neither were any of my "students" - it just so happens that all of us have/had some noticeable experience flying full scale. As a second vote I would choose FT Flyer - classic form factor, easy to (re)build and to do it light, large wing/small wing loading, self-stabilizing. If you can, make it bigger than the original. Also, paint it with some very bright, contrasting colors. It helps more than you think.
For the first flights, I would recommend doing it in few steps:
1 - "glide tests": throw the plane with zero power, straight and level - no up or down, exactly at the horizon, making sure wings are horizontal as well (it's a surprisingly common mistake to throw the plane "banked" to one side). For the short duration of the flight, just focus on keeping the wings level with ailerons (4-channel plane, like Storch) or rudder (3-channel, like Flyer). You may pull the elevator SLIGHTLY just before the plane touches the ground - so called "flare".
2 - progress to powered flight, straight and level, or as I like to call it - "walking the plane" (because you will walk quite a lot between flights): do exactly the same thing as 1, but before you throw, add a little power - very little, not enough to make the plane fly level and definitely not to let it climb. Fly as straight as possible, wings level. KEEP THE POWER CONSTANT during the entire flight. Since the plane will descend slower than in the glide tests, you will notice you don't even need to worry about the flare - just remember to cut off the power to zero just before touch-down.
3 - maintaining level flight: keep adding power before the throw, in small increments, up to the point when the plane maintains level flight, exactly at the height of your eyes. At this point, start practicing changing the power during flight. Just a little bit, back and forth, to let it climb for a moment, then descend, then climb again. Still try to keep the wings level and fly as straight as you can. And don't forget to land the plane while you can still see it.
4 - small turns: when you learn to maintain the altitude, introduce small turns. First, no more than 30-45 degrees to one side (change the side every few flights obviously). Use small bank angles when turning, then return to straight flight (wings level), then land. When this will go smoothly, make the plane turn 90 degrees - but not more, to avoid loosing orientation. Then start to make turns in both directions during one flight - for example 90 degrees left, then 90 right (at this point the plane will fly away from you again). Keep the altitude steady - don't let the plane climb (easy to forget when you are excited about the first controlled turns). At the end of this excercise, you should be able to fly side to side, making 180 deg. turns (after the initial 90 deg.)
5 - and the final step - flying towards yourself. When practicing 4, make/let the plane climb a little, and also to fly away from just a little bit more than usual. Then, start to make 90 degrees turn in one direction, flying in a "square pattern". Keep the bank angle low. Focus on making the turns close to 90 degrees, always in the same direction (again, change directions every few flights, but keep it the same during one flight), and the flight between turns as straight as possible. And try not to fly overhead.
Those 5 steps should get you to the point where you can decide when/where to fly straight or turn, how much and how long, to get the plane to the place you want it to be. And hopefully without many crashes, or at least many repairs/rebuilds. After that you can start expanding your "envelope" by adding elevator (finally! but slowly) to see how the plane reacts, making the turns steeper, using the power more aggressively etc. Please remember that all of this is just an advice - you don't have to follow it if you don't want to. Good luck, and have fun!
