For Linux users there is a very good set of macros for LibreOffice called ComposeSpecialCharacters to be found as a simple .oxt file at extensions.openoffice.org/en/project/compose-special-characters
One just loads the file and it sets it all up for you. Therafter you can set a shortcut key (I have always used CTL-z) and then when you type, eg. “a-” “t.” or “n~” and press CTL-z, it converts them to ā ṭ ñ respectively. It only works when you press the shortcut key, so it does not interfere with typing normal English, and since it is a LibreOffice system, it can work just as well in Windows, using LibreOffice. It also provides French accents, and quite a number of other useful but awkward characters, even Greek.
In Windows there is a very powerful program called Keyman, produced by a company called Tavultesoft, for a very wide range of languages and scripts, amongst them a Sanskrit/Pali (Romanised) keyboard. The program is free for up to two keyboards, so one could have Pali and French, for example, and all for free. The system offers you a choice of keyboards on the Tool Bar, and one can switch with a click to the keyboard of one’s choice. It is a very efficient system, and typing in a foreign script can be effectively as fast as typing English - depending on your skills, of course! They keep it free for up to 2 keyboards because it is used by a lot of missionaries to translate the Bible into various languages, and they do not want to victimise them.