From a person who once seriously thought about buying a new computer (!!) because I couldn't face going through all my files to reduce the sizes heres a couple of tips I have learnt over the years...
1. Don't just load and forget - once you have taken your photos go through them and remove the duplication. Pick the best one and trust me, you will never miss the other 20 taken in the same 2 minutes!
2. Go for moments over looks! Photos are about preserving moments - if the moment is precious but you hate how you look then keep it. In 5 years time not only will you think you look fabulous but you will have that memory saved too.
3. Fix as you go. I shoot everything in RAW and nothing gets saved until its been looked at. If the exposure isn't quite right or it needs cropping or straightening do it now - you won't do it later.
4. Back up!! I lost my eldest daughters first birthday photos through not doing this. What ever method works for you but make sure it is easy to access too.