In order to get the best GPS signal as possible, and thus, a better accuracy for your navigations during your outdoor activities, you should consider the following tips:
1 - Go to the least enclosed outdoor area possible (with a good view of the sky).
2 - Remain stationary.
3 - Cover the GPS antenna as little as possible: Position the GPS vertically, the antenna is on the top.
4 - Hold the GPS vertically: It is advisable to carry the GPS vertically facing upwards (either in carrying bag or on the strap of the backpack).
5 - If the device is placed on a bike handlebar, keep it in a forward position to avoid anything in the way of the antenna (piece of handlebars, brake cables...).
6 - The device must not be near interference such as eBike displays.
Note: On recent devices like Terra or 'Plus' models, turn on the 'Use Assisted GPS' option from 'Settings > System > GPS Settings > Assisted GPS (AGPS)' and make sure it has been updated within the last few days.