Welcome to the forum!
Are you planning to just collect, or do you want to trade, as well?
Here are my tips:
For collecting: Set a budget! Decided on a theme or focus for your collection. (You can always change this later, or add new themes! When I started trading, I simply wanted "cute animal pins." I quickly decided to focus on just a few particular animal characters (Figaro, Chip & Dale, etc.) and over the years added Peter Pan, Alice in Wonderland, Robin Hood, The Sword in the Stone, and holiday pins to my growing list of collections. THERE ARE SO MANY PINS OUT THERE. It can be overwhelming.
Make a PinPics account and look at all the pretty pins. Make a wants list of your favorites. Next, look at your favorites, and see which ones are smaller, cheaper, or easier to find. Being a newbie, these are the pins you should start trying to get! They tend to be open edition (in other words, there's not a limited amount of them). Hidden Mickeys (a type of smaller pins cast members have on their lanyards), pins from mystery boxes, pins from booster sets, and "rack pins" (pins regularly available a the Parks) are all good pins to start trying for! Limited edition pins tend to be a lot more expensive and harder to trade for.
IF you plan on trading in the future: Always use a bubble envelope, as well as bubble wrap. Pins DO get broken in the mail and it SUCKS when that happens. If you plan on printing out your own shipping labels, invest in a small postal or kitchen scale, because you will need to know the weight of your packages. If you decide to take all your packages to the post office instead, make sure to KEEP YOUR RECEIPT. It will have your tracking information on it. Always ask for tracking (it comes free with regular/first class mail these days). It's good to send to the person you're trading with, and it's also proof that you're not at fault in case the package gets lost.
Another tip: Whether or not you plan on trading, if you have a cell phone, download the app "Aftership" - It keeps track of all your tracking numbers for you (sending or receiving), and lets you know whenever something has been delivered. Super helpful!