完 says you used it all up. 好 says it is ready to use

Where the picture shows up in 好

1. 1

   ready to eat

   饭做好了，快来吃。

   fàn zuò hǎo le, kuài lái chī

   Dinner's ready, come and eat.

   The rice cooker lid up, steam rising, the rice sitting there needing nothing but a bowl.

2. 2

   booked and holding

   位子我已经订好了。

   wèizi wǒ yǐjīng dìng hǎo le

   I've already got the table booked.

   My name written into that time slot on the booking sheet, the table held for me.

3. 3

   properly fastened

   安全带系好了吗？

   ānquándài jì hǎo le ma

   Is your seatbelt properly on?

   The tongue of the belt clicking into the buckle and not letting go when you tug it.

   系完了 says the fastening motion ended; 系好了 says the belt is actually holding.

4. 4

   ready to leave

   准备好了就出发。

   zhǔnbèi hǎo le jiù chūfā

   Once you're set, we'll head off.

   Bags packed, shoes on, standing with your hand already on the door handle.

5. 5

   fixed and usable

   我的电脑修好了。

   wǒ de diànnǎo xiū hǎo le

   My laptop's been repaired.

   The laptop's back panel closed again, the screen lit, the machine handed back into my hands.