First of all, think about which MCSE you want, since there are several variations:
http://www.microsoft.com/learning/en-us/mcse-certification.aspx
If you are thinking about the "old" traditional MCSE (Systems Engineer), probably the closest "modern" MCSE (Solutions Expert) would be the MCSE:Server Infrastructure. But there are some newer specializations that you might find interesting
if you are pursuing a career change. Perhaps a MCSE:Private Cloud or a MCSE:Sharepoint, or any of the other several variations.
If you follow the link that I provided above, you can click on any of the MCSEs and go to the page that lists the exams that you will need. If you then click on any of the exams, you will get to a page that contains a section for "Skills Measured" as well
as "Preparation Options". First of all read the Skills Measured to see how many of the required topics are already familiar to you. If you are only missing a small number of items, you can simply search the Internet to find relevant information such as articles
on Technet or MSDN, and this may be enough to prepare for the exam. On the other hand, if you are missing a lot of knowledge, then it may be preferrable to take a course or buy a book (see Preparation Options).