How changing hosts wll affect my site

i have my site hosted with an account which allows 20 mb space and 1 gb bandwidth. i started with this provider as i did not want to go for bigger accounts initially. Now traffic has started rolling in and my site is also increasing in size. So i am thinking of changing host as i want to go for a more reliable host and larger space and bandwith keeping with the growing demands.
My question is , how will changing hosts affect my site ? what are the possible problems that might occur which i need to take care of ? will it cause problems with the search engines , specially with Google ?

As long as your site never goes down you won't have a problem with changing hosts.

1-Get the new hosting up and running.
2-FTP all the files to the new host and check the site to see if it's all working properly (you can check it through the IP adddress).
3-Once it's all working properly, change the nameservers with your registrar.
4-keep the old hosting/site up and running for at least a week to make sure it's all been moved properly.