Hi, Mr. Schulz, why is it that you say hello to Mr. Kuhman but not to me ..
Yes, I know your real name from PM and also from some other people of this forum. But I don'l like nicknames and I never use it within a greeting formula. I respect it, if people want to hide themselves. It is something else, if people here use a real name. If so, I'll use their first name for greetings.
Hence, in particular cases, we do need to remember the manual install methods.
Yes, but the use of apt or aptitude is a manual install method and nothing happens automatic. I prefer aptitude.

If you use "aptitude install foo", then aptitude tries to find a solution. If there are problems, aptitude offers to look for other solutions or to quit. Perhaps, one of the other suggestions will fit. If no, you can try "aptitude install -t stable foo" or "aptitude install -t testing foo" or one of the many other options of aptitude.