How do you manage warm-up routine(s)?

Like many self-taught singers, I did not know the importance of properly warming up for a long time. Now that I do know, however, I find it tedious to do the same exact routine every time. Having to accompany myself on piano (or play a warm-up video each time) is tedious, too. I would like to prepare a set of warm-up routines that I can pick from before each session.

How do you manage this? Do you use any apps that help you warm up? Do you just pull out the piano every time you sing? If you don't have a piano, what do you do to warm up? If you take singing lessons, how does your routine when practicing solo differ from what you do in a lesson?

Thanks in advance for your responses. I don't have the option of in-person lessons right now, but I figure that asking a community like this for their opinions is a good idea.

P.S. The lessons on this site, as well as the live group lessons, are awesome!

Thank you, Tobe!

My personal warmup usually looks something like this:

Lip trills (or straw singing), in a relatively comfortable range

NG or syllable with EE (into high head voice)

MUM/NUH into mix range

ONE into mix range

Optional: fast-moving scales for riffs & runs; sustains (if the song I'm about to sing requires sustains)

I just let my voice guide how high or low I take each exercise - although if I'm about to sing a song with a difficult section, I do warm up to that specific note (or a little past it). 

I typically don't use the piano for myself, since I can trust my ear for tuning (but I do check in every now and then with the piano or piano app); I just move the pattern up or down one semitone at a time. 

Hope that helps!

Thanks, Camille!

You're welcome!