You can directly upload GPS traces:

https://www.openstreetmap.org/traces

That won't get them into the OpenStreetMap database, but it makes them available (if you set them to public) for anyone looking to add the trails.

There's also apps like StreetComplete. It has 'challenges', where it prompts you for answers to questions and updates OpenStreetMap accordingly (so what is the surface type of a road, things like that).

Vespucci is a full featured editor for Android.