Next, gather the correct tools. Yes, that's right, you will need your manual. If you've misplaced it, go order a new one. You need it anyway. Though sewing machine has certain common attributes, each machine is slightly different in how it is constructed.
Some machines have front loading bobbins, some have top loading bobbins.
Some machines require a tiny bit of oil in a hole on the top of the machine, some do not. Some machines have to be opened to get at the innards. Other machines cannot be opened. It is vitally important that you read your sewing machine's manual to learn the oiling points. Do not oil the machine at any point except where the manual directs, even if it looks like it needs oil there.