If there is only one tip to take away from this site in regards to your collection it is this:
There is no "right" way to collect.
It took me over 40 years as a philatelist to finally internalize this lesson and start collecting what I wanted to collect. There is no rule carved in stone that says that you can only have one collection, and that it must be complete. Completion, is an arbitrary term anyway. Complete according to what? A collection can be complete, as far as having one of each basic stamp from a country or a period, but can be woefully incomplete from a specialist's perspective. You can have as many collections as you want, and I find that having several different collections is an ideal way to get the most enjoyment that you can from this hobby, for when you become frustrated or bored with one, you can set it aside and pick up another. You may find that you have several different "needs" as a collector, and that trying to have one collection satisfy all needs is difficult.
For example, I like collecting modern paper varieties, but I also enjoy collecting shade differences and plate flaws on classic engraved stamps. However, because I am a dealer, I really do not want to collect expensive material, because I want to be able to offer it to my customers. Therefore both of my collections are comprised of relatively inexpensive stamps: British Commonwealth Omnibus issues to the mid-1970's to satisfy my desire for classic engraved stamps, with a splash of modern, and Canada from 1947 to 1997 to cover my desire to collect paper varieties.
So, you should collect what you like, and do not be afraid to start new collections as your interest takes hold, and leave material you do not particularly like out of collections you are forming. Unless you are planning to exhibit competitively, there is no good reason to collect stamps you do not love.
You also need to be patient, and understand that there is plenty to go around for everyone, at least for the modern stamps. Unless you are collecting rare stamps, there is more than enough in existence to supply most collectors, especially if you are not a perfectionist. Therefore, you can relax, in the knowledge that if you miss out on a stamp you wanted, you will see it again, and will have many chances to acquire the stamps you want.
It is a good idea to watch your tendency towards perfectionism. With the amount of ego involved in the hobby, and the status that tends to be conferred on collections of stamps in extraordinary condition, it is very, very easy to get drawn into being a perfectionist with your collecting. The problem with perfectionism that gets out of control, is that it can seriously hamper your fun, as you will tend to see only the imperfections of the stamps you have, and not appreciate their beauty. A good cure for this is to collect an area for which material simply does not exist in the higher condition grades. If you do this for a while you will very likely find that you have just as much fun studying and collecting stamps in fine or very good condition, as you do collecting the higher grade material. There is nothing wrong with pursuing quality of course, but you will find that you will have much more fun if you avoid getting obsessed about condition - appreciating the extraordinary stamps in your collection for what they are, rather than taking them for granted and expecting all your stamps to be like them.
Another good idea to adopt when you are going through a "tight" patch with your finances, is to spend time arranging your stamps, writing them up, or researching the subject matter on the stamps. This is one aspect of the hobby that often gets overlooked, as many collectors do not feel like collectors unless they are constantly acquiring more and more stamps. But, the reality is that there are only so many stamps that you can look at in one sitting. So, having more stamps, while it is always nice, is not the only way to enjoy the hobby.
Lastly, try to remember that at the end of the day, it is a hobby; nothing more, nothing less. It is here to give us pleasure - a way to unwind and relax, while still being connected to humanity on some level. If you keep that firmly in mind, you will find that you don't take the hobby too seriously, and will have much more fun with it over the long term.