1. One of the most important things to consider when buying lingerie is sizing. The best thing to do, if you don't know her size is to check her lingerie drawer to see the size of her favourite items.
The bra size will consist of numbers and letters for example 32B, 32 would be the chest size and the letter is the cup. Knickers are the same as normal dress sizing.
2. The next thing to consider when buying Lingerie would be the style. Are you looking for something flirty, glamorous or understated? You should also think about whether you are looking for a bra and knicker set, chemise or corset.