[dmm]

If you send a ship out too far, don't despair. Bring it back as far as you can, and send another ship (or a fleet) to meet it. They can share supplies and all get home. This is a nice trick in the early game, before solar collectors and space yard ships.

Another good range-extending tactic is to get a military alliance with someone far enough away that you're not competing for the same systems. Then you can use their resupply bases. In a huge galaxy, you might use this to leapfrog across the whole galaxy, then trade colonization techs with those distant neighbors. (The heirs to your throne might regret that decision 100 years from now, but, hey, that'll be their problem.)

You often want a competing empire's planet mostly for its population (for instance, because they breathe a different atmosphere). So, after obtaining the planet (and presumably angering the other empire), take a bunch of the pop and then give the planet back. You may be able to avoid a protracted war, and still get what you really wanted. (BTW, I find it annoying that you can trade all sorts of stuff, but not population. With human players, though, you can sometimes make this kind of deal in advance. Related side note: Players with different colonization techs and different atmospheres who ally faithfully from early on will be very hard for outsiders to beat. Just watch out for mimic intel ops!)