Use the built in permalinks and it will create htaccess file for you if needed. settings>permalinks this is my preference: /%postname%.html but there are many others. The reason I link this way is because so many people who do not use WordPress are used to seeing an .htm or html extension and will often type it in when they are manually linking back to your page. If you leave it up to them to choose to add or not add a trailing slash you divert your SEO potential.