Scoring hosts is a very important part of the Sia Network. Every host receives a score based on their participation. Having a better score will allow you to receive more contracts than others.
Having your host available and accessible most of the time is very important. The max your system needs to be available is 98% of the time. There is no direct benefit for having more than that. This allows you have about 14 hours of downtime a month for system maintenance.
If your uptime starts to decrease, you will be penalized for your offline time. There is not very much punishment for decreasing to 95% uptime. But if your system is not available more and more, the punishment against your host will get more severe.
Storage price is one of the most important parts of the scoring process. Renters will obviously consider price as they select hosts, and will be reflected in your score as such. Storage pricing is a smooth function, so decreasing your storage cost by 1% will have an impact.
When you form a contract with a renter, you must put up an amount of collateral. This amount is held in the blockchain and fore-fitted should the host not meet the obligations to store the data for the length of the contract. As such, offering a higher collateral amount is preferential to the renters.
Running an older version of Sia will result in a lower score. Newer versions will have bug fixes, scaling improvements, performance improvements. This was implemented to encourage hosts to stay up to date on their installations.
Long ago, there had been a problem with renters forming contracts with hosts that were low on space. This caused renters to form contracts but ultimately not be able to store data. Up to a point (more than 4TB available), hosts are rewarded with having more data available.
Lifetime Adjustments will adjust the weight of the host according to the total amount of time that has passed since the host's original announcement. Being a host longer will result in a better score.