Imperative followed by "rather than"?

Rather than is used both as a conjunction for infinitives and as a preposition.

In this example, rather than is a preposition, with a gerund as its object:

Shoot a single shot rather than taking many random pictures.

Here it's a conjunction linking the infinitives to shoot and to take:

She wanted to shoot a single shot rather than take many random pictures.

You can use rather than as a conjunction anywhere you can use an infinitive, including the bare infinitive of the imperative mood. (The verb following rather than is always a bare infinitive.)

In other contexts, use rather than as a preposition with a gerund. Note that some people object to rather than as a preposition, preferring instead of for the non-infinitive uses.