How to Fill a Vape Pen 101
First things first, the term ‘vape pen’ is a bit generic. There are all kinds of vape pens. Some vape pens use dry herb, wax, and oil cartridges (pre-filled and reusable, empty ones) and this will all affect how you fill your vape pen. Not to mention, not all vape pens have the same styles or features, and many will differ in how they are entirely set up to begin with, even if the most basic science behind them is the same. 
For example, when thinking about loading a wax pen vs a dry herb pen you have to keep a few things in mind. Dry herb is not as dense as wax and not nearly as sticky. But dry herb can go flying anywhere if you’re not careful about how you’re handling it and can be lost to the wind, etc. Wax, on the other hand, needs to be carefully handled to prevent it from sticking to you, your dab tool and other surfaces. With a more liquid-like wax, the wax can flow more easily so you will need to watch out for spillage too.
Different vapes can also present different challenges to you. For example, a glass globe vape pen might be more sensitive to damage because of the, well glass globe that can shatter if bumped the wrong way.  A box mod might be less handy to carry around with while traveling than a smaller, more discreet vape pen. Or, smaller vape pens might be more difficult if you have bigger fingers (think about how much of a pen it is to text sometimes).  Below we list out some popular vapes and generally how to fill them, but ultimately, at the end of the day, to know the exact way to fill a vape pen, you may need or want to look up that specific vapes user manual or some other guide to using it.  

How to Load a Vape Pen with Oil
The most important part of filling a vape pen with liquid is going to be to make sure that you are keeping good track of the liquid itself and not letting it spill everywhere. So, you will probably need to remain stationary to avoid dropping oil all over yourself, your vape pen, and the area around you. Generally, you’re going to remove the cap to your vape pen and slowly, carefully begin put the oil inside. Some oil vape pens are going to be a little different than others depending on the layout of the design and different specs or features. Make sure you are looking at the product info before you purchase it. 
Another important thing to watch out for is mixing the oil. Different oils have different operating temperatures and if you have two oils that work better at different temperature and power settings you might end up making your vape pen experience less than optimal. Not to mention the flavors might not taste good together and you may have wasted the vape oil.
Finally, and this is more of a basic maintenance suggestion: make sure to keep your cartridges clean, especially if they are refillable. Leftover vape oils and resin left behind by the flow of vapor will build up inside the vapor pathway of the vape pen.  When working with sticky, thick substances like oil or wax keeping a clean and maintained vape pen is going to be very important, so filling the proper way is of utmost importance. If you are using disposable cartridges this is obviously less of a problem because they can be thrown away after use and do not require filling. 

How to Load a Vape Pen with Wax
Wax vape pens are going to differ in terms of loading based on the different wax pens and what kind of coil you are using. Not to mention, the kind of wax that you are using as well. If your wax is more like a liquid than you will need to watch out for pesky spills and fill the wax coil chamber accordingly. Like always, vape pens are going to require specific attention depending on the coils, styles, specs, etc. However, there are some general tips to keep in mind when properly using and filling your wax pen.
One of the first things you need to understand is your coil. For example, if you’re using an older vape or a model based on older tech, you might have a wick coil. A wick coil uses a fabric wick, usually cotton, to heat up your wax. This works better with more liquid waxes and not thicker, stickier waxes (although it can still operate). Be very careful about underfilling and leaving too much exposed, dry wick. This will cause it to burn and affect your taste and performance. A quartz or ceramic coil will work better with thicker, stickier waxes. This is because they will not burn if they are a little exposed, you can dry fire it all day without issue, although we don’t recommend it. When loading these kinds of coils, go ahead and burn off any residual wax to make sure everything is clean and crisp when placing the wax in the chamber.
Another thing to keep in mind is that dab tools will be particularly helpful in storing the wax and to avoid getting sticky and covered in wax. This will minimize the amount of interaction you have with the wax itself and it is worth the investment to avoid having to constantly worry about getting wax everywhere. Dabbers, the tool to handle the wax, comes in a variety of sizes from short to long, sharp for precision and flatter for handling larger amounts.  Use a dabber to load the wax coils but NEVER poke the coils directly and try to avoid contact at all costs.  Just gently push the ball of wax towards the coil and the heat should do the rest while you are vaping.
In addition, you will want to make sure you don’t overpack your wax pen. This will cause it to strain and could contribute to the vape pen burning out, and in either case, over-packed coils will overflow when the wax bubbles-up from the heat produced by the coil.  This wax can get into the mouthpiece, make it difficult to remove the various vape parts and more. 

How to Fill a Vape Pen with Dry Herbs
So, as always, you’re going to need to be careful filling a dry herb grinder to make sure that you’re not spilling dry herb everywhere. As it is a different composition than the wax or oil try to avoid being in a windy place. Another thing to keep in mind is that you’re going to want to avoid overpacking the heating chamber because the hot air in the chamber needs space to flow and heat all of the herbs.  For the best results, you will Need to use a functioning dry herb grinder that is able to make a fine grind. This helps vape the dry herb more evenly and will also make it easier to pack.  Without the space and especially with dense unground nugs, it can lead to uneven heating, negatively impacting the vaping experience, most specifically taste. 
Moreover, you need to see if you have a combustion or convection dry herb vape. This will affect how much you need to pack and how you need to operate and fill your vape pen. For example, a combustion vape will use an exposed coil, and that heats the herbs creating smoke and leaving the chamber with ash. A convection vape will operate more like a conventional oven and create vapor and not smoke. Both require proper heating chamber packing, however, a combustion vape pen might need to be stirred in between vape sessions given that it is igniting the dry herb from the bottom up via a hot coil – versus combustion vapes that heat like an over.

Tips for Filling a Vape Pen Carefully
For one thing, there will likely be extra things you can do that will depend on your vape pen. Think specific tips and tricks.  In general, there are some things you can look out for to make sure that everything is going well. For example, check out all the different tools and accessories available to make it easier to more precisely and carefully pack your vape pen. You can buy little dab tools for your wax pens, syringes for your oil pens, and even small scoops or items to more precisely measure out and pack dry herbs. These will help make sure you are accurate and not spilling your stuff everywhere. Another thing is just to make sure you are careful about not filling it on the go or when you’re in a rush – if you will be, for dry herb vapes you should make sure to grind the herbs in an herb grinder before you leave the house – for wax pens you can pre-pack the coil but we recommend bringing a small dab container and a dabber tool inside a plastic bag. Also, lighting helps a lot when filling any vape pen.. Just being able to see will make sure you don’t overfill or leave exposed coils and other parts.  

How to Re-Fill a Vape Pen
One thing to keep in mind with refilling your vape pen is that you will pretty much do the same thing you did the first time around. However, when reopening the heating chamber and going to refill it, you want to be careful that any residual wax, oil, or dry herb/ash are not going to fall or leak out. Basically, just be extra careful and make sure you give it a once over before ripping open a wax coil or heating chamber when looking to re-fill your vape pen again. 

Can you put Water in a Vape Pen
Almost universally, no. Absolutely not. Oddly this has been asked.  You should only put water in a vape pen if you are specifically told to do so (which you will most likely never be told to do).