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I guess the first question would be how do you want to capture your ideas?
If you have a decent laptop or computer you can use a DAW with an audio interface. *Cubase/nuendo, protools, logic, studio one, reaper, are a few examples. For basic tracking they all do pretty much the same thing. The workflow and the price-point is the main consideration while you're just starting out.
For Audio interfaces, there are quite a few out there. It depends on your budget. like, the Behringer U-phoria series is probably the cheapest, and the Apollo ones are on the top-end. I'd recommend going onto amazon to browse and read reviews if that's the way you want to go. Just remember, you usually get what you pay for, so if you can afford to spend the $$$, then get the best you can.
Or you could use a built-in recorder that captures to SD card (like someone mentioned the zoom R16) I had one of those for years, they're mobile and useful, but the preamps aren't the greatest. but it gets the job done.
other considerations, will be how many channels you need. will you want to use mics (if so do you have a nice quiet room?), or a direct-in signal? I'm guessing you could probably get by with a 2 channel (for most purposes) or an 8 channel if you need to track drums, or want to go all out with lots of mics.
Sample rate and Bit Depth are another consideration. this will look like (sample rate 44,100 48,000 96,000) (bit depth 16, 24, or 32, bit) Just use the highest you can get away with. but the higher you go, the more cpu power you'll need, and the more storage space your sessions will take up
Gain staging - once you're setting up to record, set your input gain to the highest you can get without clipping. I'd recommend doing a google search for 'signal to noise ratios audio' or 'gain staging audio' to figure that part out. basically, you want the 'hottest signal you can get without clipping or introducing too much noise'
As far as sending your tracks off for mixing. Your engineer will probably ask you to consolidate your tracks. which basically means you export your tracks individually, each beginning at 0:00. This allows for the engineer to easily align them in the new mix session.