I don't know quite how much of a beginner you may be.So please understand if this seems like very basic advice but I would suggest getting some of the really cheap bits with tungsten carbide edges and begin by taking your designs and cutting them in foam until you are comfortable with all parts of the process and can be confident that the piece coming off the machine will be exactly as intended.At which point you can move to wood and gain a bit more experience.You don't mention the type of machine but I will caution that some of the feed rates recommended for commercial machines will run the risk of stalling either the spindle or steppers of a hobby machine ,unless you have got hold of something unusually powerful.Intentionally cutting metal on a router is something I have done very little of and can't offer advice beyond considering it as high speed machining of metal and if you look around there is an amount of information out there.