Welcome to ECF. Pretty new to the forums myself but I can try to point out a couple of models to look at for various situations.
1) Batteries you stated something inconspicuous and can be pocketed I'd go a couple at least 2 JoyeTech Ego-C Twist (Vision makes a version called the Spinner basically the same battery setup with a dial on the bottom to crank voltage up and down) with a USB charger cable and wall adapter, maybe even a car cig-lighter adapter in the kit, 650 mah rating (mah = milli-amp hour, higher this rating the longer the battery lasts before needing recharging. These in length are about the width of a hand so pretty compact and can be fit nicely in a pocket, so can be great for out and about, at work, etc. Keeping a case to carry the extra battery, charger, adapter, and couple extra attachments like cartomizers, tanks, drip tips, extra bottle of juice can work real well. They have 2 type of threading, internal 510 thread for basic cartomizers, cartomizer tanks, drip atomizers, etc, and external Ego Cone threads which can accept clearomizers with this threading like the Kanger T3s, Evods, Vision Stardust (CE4) etc opening up your range of attachments you can use. Another alternate to the Ego like the Vision would be a Kgo also.
2) An at home battery, again you can go with a 650mah battery, doesn't have to be a variable volt like the twist or spinner, but one with a "usb pass-through" would be highly advisable but not necessary, but has the benefit of it is connected to a cable with a usb plug in at the bottom, as you use it, it continues to keep the battery charge topped off, great for next to your recliner as watching tv and such.
Attachments
1) Cartomizers are great in they can be prefilled, compact, pretty inexpensive, and easy to maintain. Look into Boge or SmokTech 510, standard resistance (2.0-2.5) ohm, want the liquid to last longer between refills look into the XL or XXL size to start off.
2) Couple Atomizers with drip tips. These are great to test flavors with, couple drops, 3 to 4 in it, plop a tip on, put on your battery, fire away to check how a juice is going to taste to your pallete, great to have around if you visit a brick and mortar juice vendor, great for at home when you need a break from your normal vape liquid with another flavor for a bit. They produce the best vapor, taste, and throat hit.
3) Tank style attachments. Clearomizers, DCTs (Cartomizer Tanks, tanks that house a normal cartomizer that has been punched, slotted, or drilled with hole in the side and extra liquid outside the carto) if you really like cartomizers, more liquid storage for extra mileage during the day between refills. Clearomizer tanks like the Kanger T3, Vivi Nova, and such use a wick leading into an atomizer head, these can be top coil (generally a warmer vape as the coil is at the top) and bottom coil generally cooler vape as the coil is at the bottom, but has the added bonus of you don't have to keep tipping the tank to keep the wicks wet, similar in fashion to how a DCT works.
First kit I would order as a suggestion, one with a case, charger, wall adapter and car adapter if you have to buy extra do so, should have 2 batteries, 2 Clearomizers or some type of tank, preferably one that the heads can replaced like the CE5s, Kanger T2s T3s (MT3), Evod, Vivi Nova, etc, at least one 510 atomizer, one drip tip, bottle of juice at least 30 mililiters in your prefered nicotine strength (nic strength measure in miligrams per mililiter (18mg or 1.8% are same strength as an example). Probably $50-$80 USD should be a good starter kit price. Getting a pack of blank cartomizers if you find a clearomizer isn't your thing on hand to fill and cheap to replace is advisable, and if you really like cartomizers, later down the road look into the Carto Tank Systems.
Little bit of a long post, but hopefully I've given some aswers to point you in good direction and good luck.
