Hi Sam
All good stuff above. All I would add regarding how long to model is that it’s natural when you start something new to want to do it all the time. That keenness will eventually wear off, and you will do less. It really isn’t a problem, you will eventually settle to a rhythm.
During some builds you will find things aren’t going your way, or a certain aspect is really tedious, and you want to give up....that is also natural. The secret, if there is one, to overcoming that problem is to start mentally breaking the build or paint process into small operations and plan to complete one process at each sitting. That way you will see progress and that will feed the mojo to allow you to continue. Remember, you can only eat that elephant one bite at a time....
Other advice I would give is to occasionally work outside of your comfort zone. Making Tanks, Trucks, Aircraft, Cars, Trains, Motorcycles, Figues, or Busts are all aspects of modelling, but all require slightly different skill sets. Occasionally building an aircraft if you normally build tanks, for example, can give you a different view on the modelling world and refresh your interest. You may find something you really enjoy that you never considered building before.
Don’t get overly hung up on detail. Nothing kills the fun more than obsessing over things like scale colour and hyper accuracy. I know, because I got there once and gave up the hobby for about ten years. These days I mostly build out of the box.
Lastly, it is far easier to spend money that time. Most modellers could probably forego kit spending for several years and not run out of subjects. That is also normal.
Don’t fall for the “latest and greatest” hype in kits, paint or tools either. Learn to use what you have, trying something a little different for each new build...this will increase your skill set faster than anything. After all, you don’t get to sound like Eric Clapton or Angus Young by buying a replica of their guitars, no matter how well made they are, you get there by putting in the hours and expanding your knowledge base.....
Go with the flow. If you start getting frustrated or burned out, switch it up and vary what you are doing....and never think “I can’t build like X, or paint like Y”. Perhaps you can’t.....yet......but remember, they have the same hands, eyes, and brain that you do, so if you work the problem you’ll get to where you want to be.....and they may well be thinking “I wish I could model like that Sam blioke, he’s awesome”....
Cheers
Tim