There are simple search instructions on the previous page. If you can't find what you need or are getting too many results and want to narrow down your search then the Advanced Search is useful.
The Advanced Search for maps can be found here. It gives you more search options - Place is the area covered by the map, and Subject is for maps showing a particular subject (such as geology, railways or population).
The image below shows a search for maps where Place contains England and Subject contains geology, with some of the search results.
You can keep adding lines to refine your search - the screenshot below shows the previous search, with the addition of Map Scale contains 50000:
If you don't know what scale maps are available and want to find out, you can search by place and narrow down your results using the Map Scale facet, shown below. This comes quite far down the list of facets, on the left hand side of the screen under "Sort and filter results." It is available on both the general search and specialist Map Search screens.
One important thing is that detailed maps of a specific area are very often part of a series covering the whole country, which will be catalogued under the name of the country. There's more information under series mapping.
You can search by Publication Date to find maps of a particular period - use the ? symbol for truncation to limit your search to maps of a particular decade. Here's how to search for maps of London from the 1660s:
Using 16** in the same search would find maps of London from any time in the seventeenth century (you have to use * rather than ? if you are replacing more than one character). Searching by date will find both facsimile and original maps from the period specified - so if we have a modern copy of a 1660 map, you would find that as well as an original.
Early maps were often printed in atlases and are not always catalogued individually; there is more likely to be a single record for the whole atlas. Please consult Bodleian Map Room staff for more help with this.