I've heard that doing family history without maps is like painting with your eyes shut. If you try without, then find a good map you'll understand. For a few years there has been a great set of online parish maps for England but until this month Wales was not included. The site has not been fully updated and additional functionality should be available soon. The parish maps for Wales are available now and that is the critical data. The rest will be a bonus.
Visit the website maps.familysearch.org where you should see a map of England and Wales. The search feature does not work yet but don't give up. Click on the zoom feature (+ symbol) on the upper mid-left portion of the page. You may need to click on the zoom button a few times until the parish boundary maps start to show. This is great if you know where an ancestor lived. If you don't have a county and place within the county keep checking back to discover when the search feature is updated for Wales.
I've been researching an Owen family from Penegoes, Montgomeryshire recently. Being able to see the outline of the parish boundaries is very helpful as I consider a burial entry for Jane Owen of Penegoes in the Machynlleth records.