I would doing the following (I was the QA/QC manager at two different companies where I put together GMP/GLP laboratories):
1. Go through the following documents: 21 CFR 210 and 211, GMP standards, and 21 CFR 58, GLP standards. Even though it may be hard to believe, these are the only requirements to satisfy GMP/GLP standards. In my experience GLP standards are more clear than GMP, so when it comes to SOPs and other quality documents you will get more from 21 CFR 58 than 210 and 211, even though both to a great extent overlap in their requirements. Both of these documents are free.
2. The biggest hurdle you will likely face as you get started is where to begin. A good document that will help you with this is the following: ISO 17025:2005. You can buy this standard for about $90. The nice thing about ISO 17025 is that it is an international standard that was written based on GMP/GLP standards.
[Historical perspective: GMP standards were published in 1963 (check this site for some history behind the reasons why the United States had to write GMP standards; it is a good way to gain some perspective behind the reason these standards exist). GLP standards came a little later (made effective in 1979) and their main intent was to support GMP standards, but since then have become their own standards (regulating non-clinical labs; clinical labs are regulated by, you guessed it, GCP standards and CLIA). ISO 17025 came later still (in 2000) and was written based on all that we had learned from GLP and GMP standards]
3. A good place to start is: write an SOP on how to write SOPs. This will define the contents of all your documents. Format and content is key (21 CFR 58 describes this). Along with this document you will need to put together a QA manual. That is where the ISO 17025 document comes in handy: you can use it as a guide as to the contents of your QA manual (along with the 21 CFR 58, 210, and 211). Once you start getting familiar with these three documents you will realize how much overlap there is, and that will help you get a better idea about how to fulfill each requirement.
GMP standards are to a great extent a matter of interpretation. Unfortunately a lot of it has to do with experience (when you get audited you will find out what you have and what you are missing; there is no way around that), so all you can do is put the best system you can and then be ready to work on it when an auditor finds that you are missing something. In rare cases you can argue with an auditor that asks you for something that is not truly required. But I strongly recommend not doing that until you have at least a couple of years, and a dozen or more audits, under your belt as a GxP laboratory .
If you have any questions or need additional help feel free to contact me.