When you choose your first e cig kit we generally go for the cheapest. A standard e cig kit such as an ego ce4 type kit can be bought for very little money nowadays but it will not be as good as it seems. For most people an ego battery with a ce4 clearomiser will usually be enough sway a person towards or away from vaping. When these first came out everyone would agree that they were the business but things have certainly moved on. More up to date clearomisers have changeable coils so no need to throw away the whole unit like you do with the ce4's, you can also get very good dual coil atomisers with varying tank capacities and some of the better ones even have airflow adjustment!
When it comes to the batteries a standard battery fixed output is generally around 3.3volts and will taper off quickly one battery discharges now if you use a good quality variable voltage battery not only do you get to turn up the volume but also the battery output remains static at your preferred setting. You will be surprised at how much difference in vapour and flavour is achieved by just turning the voltage up to around 4 volts. Just a word of warning though the battery voltage can only be turned up to the level a particular atomiser can handle and if you over do it you will soon be aware of a burnt dry hit "not nice".
Basically vaping is a 3 step process
1 Basic starter ie ego type
2 variable voltage " more flexible and generally safer batteries due to added internal components
Step 3 variable voltage, variable voltage, drippers RDA's etc but I will save this for another section st here.