First off, I am not a qualified motor mechanic/engineer. I am just a guy who loves motor vehicles. Especially 4x4s. Despite this lack of expert knowledge, from over the years I have gained a fair amount of basic knowledge on a vehicle's mechanicals. This helps me to troubleshoot if there was a problem during an overlanding trip and also to carry out basic maintenance work. For anything beyond my knowledge and skill level I rely on the experts at the garage I take my vehicles to.
Periodically (usually every six months) or after every offroad trip (depending on how much stress I may have put the vehicle through) I go through an inspection process which helps me to identify any tell tale signs of wear. If I can attend to it my self I will do so, otherwise I make a list (even take pictures if necessary) and show it to the guys at the garage. They will give me their opinion as to whether it is something that needed immediate attention or something that can last a while longer.
By carrying out these inspections my self I find that I get to know my vehicle a lot more intimately. This helps tremendously if i had to troubleshoot during a trip. Also the exercise saves me a fair bit of money by not getting someone else to perform these inspections which will of course come at a cost.
Over the years I have developed a check list I go through. This makes it a lot easier for me to make sure I do not miss anything. The list is broken in to the sections - Engine, Transmission, Underside, Body, Electrical, Accessories, Tyres & Suspension.
I highly recommend you do the same with your vehicle. You will be surprised how much knowledge you will gain the more you keep performing these inspections.
To help you in this process I have made my check list available for download at no charge. Use of this list does not involve any technical knowledge. A bit of common sense and knowledge will do. As I always say - work within your skill set. Leave the technical stuff to the experts.
Also worth mentioning is, this is not the most comprehensive of checklists. It is something that works for me. So if you would like to add more checks to the list, I have left blank spaces.
I hope this is of use to you. If you have any questions please do write to me through the contact page.