One unit of fuel will permit you to travel 10 units of distance in hyperspace. The number of engines your spaceship has doesn't change this, you only travel faster with more engines. So you have to do the math to ensure that you'll have enough fuel to get to a named destination and back. There may be places to get fuel en route, but you have to know where these are for certain.
There are three different types of worlds from the standpoint of leaving them. If you're starting from a planet far from its sun, point yourself in any cardinal direction (up, down, left, right) and just go. When the screen shifts to the larger view, the spaceship appears stopped, so you have time to point your spaceship in the appropriate direction. If you're starting on a satellite of a planet far from its star, save time by pointing it in the cardinal direction that's closest to the edge; you will still be able to turn on the next larger view as well. But if you're starting from a world near its sun, you have to keep track of which direction you will go next, because in the wider screen, the star will soon accelerate you, and whip you around to some other direction, so you'll have to take account of that, too.
The nose of your spaceship is indicated by the white dot. To click onto a planet, the dot must touch the center of the planet. If you aren't yet adept with the controls, or don't have your spaceship improved much, and are about to zoom past a planet, you might be able to get it to touch by sweeping the nose of the spacecraft back and forth with the thruster controls (left and right arrows). You can't sweep past the critical point and thereby lose your rendezvous, for as soon as it touches, the screen will change to a close-up. Further, you can cross over a planet )(or a star) provided that your nose doesn't touch the planet's center.