Land almost anywhere, with a plane..
When you build your plane, put parachutes on the front and back of the plane, on the top of course..
I have landed a 747 on a sloped Mountain, With good Brakes, so you dont go whizzing backwards.
Good for them contracts, where you have to land somewhere specific..
When you are near your target.. cut throttle to half, go retrograde, bring your speed down to zero, launch parachutes..
Adjust your Left and Right, A/D , if you need to go forward, just increment your engines with Shift, then X to stop. Float Down.
At 1Km your chutes should Open fully.. Making it Easier to navigate. Align your Plane with the Angle of the ground..
Upon Touchdown. Apply the Brakes.. And Hopefully You have Succeeded. Congratulations..
Very difficult to Impossible on slopes more than 45 degrees..
Parachutes.. Thats how I land my Planes.. Because I am Useless at trying to land, even on the runway at KSC..
Practise makes perfect, unless your like me, and no amount of trying will do it..
So Parachutes are your way to go..
BTW. I played a game, years ago.. . Jump, Jump, Jump, into the Lava.. Jump, Jump, into the Lava, Jump into the Lava, Etc times by 1000..
Jump, Jump, Jump, guess what? Yep, Straight into the Lava.. Three weeks into the game.. The next door neighbours teenager..
I asked him, if he could get me past the Lava Lake, with appearing and disappearing Stepping Stones..
One Go.... WOT...
He got across the Lava Lake first time...
Anyways, Have FUN.. KSP, is Amazing..