Don't use % for file growth.
Preallocate the data and log sizes based on estimated growth (that's a homework that developer and DBA need to do while planning the implementation) to minimize the impact on performance when additional growth is required.
Don't over-allocate because this will impact your backup size and duration.
Always set the limit to grow, otherwise you'll get a suspect status (at a minimum), or even worse, - server will not start, depending on what database runs to the disk limit first.
Autoshrink has issues related to SAN or very fast IO subsystem, so turn it off, you're not gaining anything having it on.