Games that give you the option to upgrade (like vehicles) Im wondering if its better to upgrade asap or ride it out?

I typically find it hard to ride it out although I doubt impossible it just makes life easier. of course at some point you need to upgrade. most of those games I played are actually weapon and armour upgrades and practically mandatory. I typically find that in the end you should have enough resources to buy what you want/need it may take longer but either way should work fine. I just like to have an easier gameplay the first go around. the 2nd time around I might save up since I know what I'm doing