Hi and welcome! Important questions - how much do you smoke now, and what kind of device are you going to be using? Dripping atomizers (RDAs) and the new-generation clearomizers ("sub-tanks") burn a lot more liquid than older-generation devices. Also, how much and what you smoked is a big factor.
I smoked about 3/4 to 1 pack a day of Marlboro Light 100s - I quit using last-gen clearos like the Protank and Evod with 18 mg liquid and cut back to 12 mg once I kicked the worst of the cravings. If you smoke full-strength cigs or a lot more than I did you might need as much as 24 or even 30 mg with an old tank. But with the new technology, you only need half-strength liquid, since you use nearly twice as much of it - right now I only vape 3 mg, though I'm more than 2 years past my quit so tapering down has definitely had an effect.
One thing that helped me - it's very unlikely that you'll find an e-liquid that tastes like smoldering tobacco, paper wrapping, and chemicals. Once you can divorce yourself from the idea that you'll be able to replicate the exact taste of cigs, the easier it will be to find your own path. Some choose bakery/dessert flavors, others fruits - I went the fruit route for the first year and a half before getting into bakery, now I alternate. You may want to pick up a few flavors/strengths to try out - most reputable brick-and-mortar (B&M) shops will have their full line available in testers for you to try before you buy. More expensive than buying online, but crucial if you're just starting out to avoid flavors you're just not going to be able to enjoy. Good luck, and keep the questions coming!