Before committing to a particular host, you need to go through the process of presales enquiries. These are some of the queries you can put forth:
General Questions
1) Years in business
2) Number of servers
3) Sites on each server
4) Testimonials
5) TOS/AUP
Server and network questions:
1) Specs of server
2) Location of Data Center
3) Data transfer speed (file test)
Security Systems Questions
1) System to prevent hackers, DDOS attacks, spammers
2) Backup features
3) Firewalls used
4) Server monitoring tools
Plan/Package Issues
1) Plan features in detail
2) Additional software provided
3) Support for databases and languages for programming
4) Version of SQL, PHP etc
5) Other installed modules
Reseller Questions:
1) Anonymous nameserver
2) Dedicated ips
3) Features for resellers
4) Account transfer from old host
Billing Questions:
1) Money back guarantee
2) Cancellation procedure
3) Reasons for suspension if case of any violation