SQL Server 2008 mirrored Database with manual failover, need reporting database
There's a few questions you need to ask first.

Are you using SQL Server Enterprise Edition?  Mirroring can be done with either Standard or Enterprise, but snapshots can only be done with Enterprise.

Are you already paying for licensing on the mirror?  There's a lot of fine print, but you basically get the mirror for free - only as long as you're not querying it.  However, if you're going to add snapshots on the mirror and offload the reporting work there, then you'll have to start paying for the mirror.

Are you doing synchronous mirroring?  If so, the mirror hardware needs to be as fast as possible in order to keep up with writes on the primary.  Adding query loads to the mirror may slow down your primary's writes, and that may be a no-go for the business.

Is the business okay with data being as-of-yesterday?  No one can be running a query while you drop and recreate the snapshot, which generally means you can only refresh it after-hours.

Do you have enough space for a growing snapshot?  If you do high-volume activities like index rebuilds or reloading ETL tables, your snapshot can grow - by a lot.  Ideally, if your database is 1TB (and nearly full), you'll need another 1TB free for the snapshot - not right away, but it can happen if you do things like rebuild all indexes.  You'll want to know your change rate, design free space for that, and implement monitoring on both free space and database growth.