Become familiar with all the parts and pieces first by looking at the manual and your Losi. Work slowly like the others have said in an unrushed manner.
Perhaps start with taking the radio tray, fuel tank, and engine out. These are things that you will remove often for cleaning. Once these are off you will see how the other parts assemblies are installed.
The front section comes off as one big chunk as does the middle and back. Work on these one at a time. The middle and rear have the least pieces. The front has the most due to the steering parts.
Have a pal available just in case you need guidance. Use an egg carton for seperating the screws and nuts. Perhaps take some photos before so you can see how parts fit together better.
It is all easy once you do it a time or two.