i think i can help here.
i do an ambient/drone thing called, 'Beta Cloud', (hence my name here).
i'm using ableton live as my daw, (i use it like a mixing board, that's pretty much how it's set up and really easy to use). worth the cost for me as i've used it for many years and it has served me well.
so i will set up several channels in this 'mixing board'.
some have Native Instruments 'guitar rig' or IK Multimedia 'amplitube' or synth simulators like NI Absynth, (an amazing drone machine!), and some samples of stuff ranging from carl sagan talking about terraforming a planet, to old russian space program stuff, to patty hearse's abduction tape, to samples i make myself of emergency rooms, trains passing the tracks, drunk women on the subway, penn station at rush hour, whatever i want.
and you can time stretch, layer, loop, reverse, effect any channel you want to also.
so anyway, you can fade each track in and out, adjust any parameter, etc. with ableton using just the laptop, or an interface, (i use an akaiapc40 sometimes)-
it looks just like the main screen of ableton and reacts live and in time.
i have recorded and played several shows using just a laptop, (a macbook pro)-

a simple interface the size of a pack of cigarettes, (a guitar rig mobile)-

and either a guitar or synth. with a synth, (like my minibrute, all analog and fun to use simple drone synth)-
the synth route all fits in a backpack, with room for a large bag of doritos and a fifth of jim beam for the train ride. essentials of the road...
and i can take a train to NYC or Toronto or any where with this simple set up, very compact and simple.
with guitar, everything fits in a soft shell guitar case, found a body glove case that has room for the laptop. nice n easy-
so the way i do it...
i simply start with something basic, layer, add another track, layer, add another, manipulate, effect, reverse, layer... until i have a nice wash of sound that i like.
so if you want to examine my process further, (not that i think you should go the way i did, or that there is a right or wrong way at all- the beauty of experimental music is to make it personal, relevant, and fulfilling to YOU), here's some videos of me doing a gig in toronto a while back.
this is completely improvised live with no preset samples, using only the laptop, software, my gibson sg, and an ebow on some parts.
you'll notice i start simple with some minor melody guitar riffs and create some pretty big shoegaze washes of sound as it goes on.
the video was shot continuously in one large performance, but i had it sectioned into 5 parts to give the viewer/listener a perspective of the 'moods' reflected in the drone/drift.
https://www.youtube.com/watch?v=JodxKvKjxB4
https://www.youtube.com/watch?v=14nAlF8mMHY
https://www.youtube.com/watch?v=rvNqXEdF0X4
https://www.youtube.com/watch?v=tS8nkM4CNFs
https://www.youtube.com/watch?v=AjJTDlwNZWg
hope i've been helpful. this process for me was daunting at first and if i've helped you find your way to do ambient/drift stuff in my long winded answer, i'm glad to have helped.
good luck and DRONE ON!!!