What is best way to get certifications?

I am a part time telephone/computer Consultant with 10 plus years in the field but with not certifications. I have worked with with Windows OS’s for last 3 years and I am trying to decide what is best direction to go to begin studying and passing Windows exams.

Should I spend allot of $ on training classes or do Microsoft online classes where I purchase from Microsoft. Keep in mind I also take care of 2 toddlers during the day. My work is night and weekends.

Any suggestions would be appreciated. Thanks…Gary