1. Limit download area as much as possible. Enormous download cause huge load for map servers.
2. Do not download high zooms for whole area. Use 'Separate mode' for downloading detailed parts, to create complex map.
3. Use extended functions like download along path, for better area definition
4. Enormous trafic caused by Locus, may cause disabling download ability or even removing map provider, so think on others!
5. Read terms of use. Some map providers do not allow map caching. Using of this function is on your own risk!
6. Try to share downloaded maps (if allowed by map provider). This prevent server overload and also speed up your own download. Build community!