Plausibility of placement

The first thing you should consider when basing a mini is the stance of the miniature you are adding to the base.  In most cases miniatures (the two legged type) will either have a wide stance, a narrow stance or a one footed stance (miniatures that are running).

You don’t want to have a fancy base that you can’t attach a miniature to due to it being overly complex or unpractical.  As a general rule, Always give your miniature a solid horizontal section of the base to stand on.

One way to solve this is to simply attach your miniature to the base before adding any basing materials.  You can then pick and choose what you want added though this limits you to the size of the resin piece you can use.  This is what I like to call simple themed basing. 

Another way is to build up your base before attaching your mini.  This does not have any restriction on what you can use in terms of size.  Always keep the mini you are using near for reference.  This is what I like to call stacked themed basing.