My entry into Access was similar to Frothingslosh's - that is, from the Engineering field. I was a mechanical designer in an aerospace/defense company (not a CAD operator like Froth, but in a similar capacity). I was promoted to the position of Configuration Manager (don't ask me to explain what that is) but in that position, I had to assign controlled document numbers. What they had at the time (the late 1990's) was a series of books. A person would sign out a number manually. These books were now my responsibility. I hate manual work but I love having work saving ideas and making THEM work. Since I had taken a programming course at the Chubb Institute (and did very well), I decided to automate the process. I thought about a spreadsheet and mentioned this to my boss (picture Dilbert's boss here). The boss said something to the effect of: A SPREADSHEET??!!! This should NOT be a spreadsheet. It should be a database!!
That got me to thinking about databases (at Chubb I had taken a course in DB2 which is the database designed for mainframe COBOL programs, and also a course in Oracle) and I had the concept. I didn't have DB2 or Oracle but I had Access on my computer. I started messing around - having no knowledge of Access but I did understand VBA from having taken Visual Basic and the syntax of VBA was very similar at the time.
I went to town. I fell in love with Access. Like Froth, I was not in the IT dept - where they had dedicated programmers. One of them took me under his wing and made himself available to me. I bought a "dummies" book and a few other basic texts. I created the program and then added to it, bit by bit. I replaced that bookshelf of lame-o log books with an application on all the engineer's desktops. They loved it.
Next job, I designed an entire enterprise software system based on what I had learned at the former job, and the next job after that, I did the same.
Each time, my system was better, more elegant, more functional, more efficient, and more intuitive and friendly to the user.
My basic approach was what was stated above - break down a project into smaller units, understand what is needed and then design a function to do that thing. Then put it all together.
One of the most important things you can do is, once you have something working - BACK IT UP - and then try to break it. Enter totally unexpected inputs in completely the wrong sequence and see what happens - because that is what WILL happen once you put it in the hands of the users.
Anyway, now I'm considered an Access guru - even by the IT dept - although I'm still in Engineering. And I never had so much fun, had such an incredible sandbox, had such a powerful tool to implement my ideas, as MS Access - my favorite computer program of all time.