Get a sample bottle of nicotine from Nude Nicotine, I'd suggest getting the 100 mg/ml strength.
Get a small bottle of PG and VG
Get a flavoring sample size of two single flavors you think you'd like.
Get a clean bottle to hold/dispense the juice (<=50 ml).
Get a 5 cc syringe and blunt needle for it.
Get a juice calculator, either online, for your phone, for your computer.
Run the calculator and put in the amount you wish to make (<= 30ml), nicotine strength, and the percentage PG and VG you want the juice to be. Pick a flavoring percentage, I'd suggest 5% for all but tobacco, I don't do tobacco and don't know how much to use. You can go to e-liquid-recipes dot com and search for the flavor and use the average as a starting point.
When all has arrived, get a clean area with good lighting. Be careful. Don't throw nicotine around.
Shake all the nicotine and flavoring bottles.
Open the nicotine, draw what your calculator said for an amount and squirt it into the dispensing bottle (DB).
Close the nicotine bottle.
Get the PG and measure that into the DB.
Close that, get the VG, measure into the DB.
Close that, get one of the flavorings, measure into the DB.
Close that, cap the DB, shake it 30 seconds or so. By 'or so' I mean at least.
Wait about a day.
Vape it.
Too much flavor? Change it next mix or reduce it a bit with VG.
Too little? Add a couple of drops of flavor until you like it.
Got a good juice, you can vape it and kind of like it? Congratulations! Now come back and ask how to expand your abilities, recipes, technique. Got a bad one? Come back and tell us how it is bad. Unlikely it will be bad as this is dead simple. I vape mainly 2 flavor mixes and have exactly zero that need steeping or any special handling.