Darkblade: If I could afford like six different test kits I would definitely go for the drops, but the economic option was a set of strips that test ammonia, and a six-in-one that measures nitrate, nitrite, chlorine and chloramine, hardness, alkalinity and pH. I'm not too bad at matching the colors, except for alkalinity and pH.
So far I am at the ammonia level marked "stressed" just after "ideal". Everything else seems to be fine, but I am having trouble balancing general pH.
Test kits are not that much; you can usually order them online for much cheaper than you get them at the local retail store.
You really only need ammonia and nitrite for the time being. pH, kH, gH are nice to "know" once, and then, I really would only check them if something went wrong. Nitrates and phosphates are nice to check once in a while, especially if you have a planted tank, but are not necessary in your situation.
However, as you can already see from the strip type test kits, they do not actually give levels, and just ranges. What is defined as "stressed"? 2 ppm of ammonia? 5 ppm? Of course, anything more than 0 would be considered "non-ideal". However, for your test strip, what is considered "ideal"? And so forth...Also, be careful with how you handle the strips and also how you store them, as poor storage conditions can render the entire box of test strips useless.
I got me a thermometer that makes no sense to read, but it has a handy safe for tropical fish zone marked on it, between around 70-80F, and I'm generally able to stay between it. I have no sense for temperature, so I accidentally go from low to high 70s in a blink when I change the water. I'm really lucky my fish is such a trooper.
Try to keep your water temperature similar to the tank water when adding it back in (make note of your tank temperature, and then use the thermometer to measure the temperature of the new water you are adding. Adjust as necessary).