#aheg

10/10 would def bang

I want to admit straight away that this is one thing I dont know much about, but I've done some research!

 I do know that alot of people advise against gluing in extensions as there are many non glue alternatives now such as linkies/microrings. 

I recommend you check out this site for basic and easy to understand explanations of each

 Vixensingsblack Alt hair guide says

What are the methods for attaching loose hair?

There are many, many methods of attaching loose hair onto your natural hair. I will cover the major ways below. This list is loosely organized from what my experience and research has told me is least invasive to most invasive.

Clip In Extensions: Examples here. Lengths of weft hair with clips sewn on to be attached to the natural hair. The length of the weft is dependent upon where the clip in will be attached to the head, with the widest being at the back of the head. To remove, simply unclip. Here is a tutorial on how to make and install Clip Ins, and here is a tutorial about how to install them, Part 1 and Part 2.

Pony Falls: Example here. Long hair falls mounted to hair ties or a clip to mimic a long pony tail or pigtails. To remove, simply unclip or undo the hair tie. Silky Kanekalon, Toyokalon, or Microfiber hair is all acceptable for this hair piece. Here is a video about how to make pony falls on hair ties. Here is a tutorial about how to make pony falls on clips. Here is a tutorial about how to install pony falls.

Pinch Braiding Loose Extensions with String Method: This is a method of braiding synthetic hair in with your own natural hair to create loose streaks or extend the hair length. A piece of string is also incorporated into the braid with the natural and synthetic. After braiding for only an inch or so, the string is picked out of the natural and synthetic hair, wrapped around, and tied off. Tutorial here. You can use a variety of synthetic hair to braid in, but it all depends on how long you want the extensions to last. For short term extensions (1 night to 1 week) you can use Silky KK or Toyokalon. For longer lasting extensions (2-6 weeks) using a higher grade Microfiber synthetic hair is suggested. The best brand on the market currently is called "Shape Shifter." Remember Silky KK and Toyokalon are very heat reactive so only use very low heat to style your hair while attached. To remove, simply snip the stringe and undo the braid.

Pinch Braiding: This is a method of braiding synthetic hair in with your own natural hair to create braids longer than your natural hair. Because this hair will not hang loose and will be braided its entire length, KK Jumbo Braid or PP Jumbo Braid is an excellent choice. See this tutorial on how to braid in the hair. At the end of the braid, you can use heat to melt the synthetic hair, a rubberband to secure it, or string to secure it. To remove, simply undo the ends by cutting, then unbraid.

Micro Rings / Linkies Strands: Examples here. A micro ring or linkie is a small ring of wire covered in plastic. Your natural hair is passed through the micro ring, then extension hair is pushed in through the bottom. Using pliers, the micro ring is clamped closed. To remove, use pliers to squeeze open the micro ring. See this tutorial on how to install. The type of hair used, again, depends on how long you plan to wear the extensions. Silky KK or Toyokalon can be used for short time spans (1 night to 1 week). Whereas Microfiber or Human Hair should be used for longer amounts of time. Remember Silky KK and Toyokalon are very heat reactive so only use very low heat to style your hair while attached. Also, your extension hair should be I-tipped; you can buy hair pre-done this way, or save a lot of money and do it yourself with this tutorial.

Micro Rings / Linkies Wefts: Instead of attaching single pieces of hair, micro rings with this method are used to attach Wefts. First, a track similar to a cornrow is made using natural hair and micro rings. Once that is done, weft is stitched onto the track. Here is a great tutorial on how to do this method. For this, you will need hair on a weft. Human hair is widely available on wefts, whereas synthetic hair is less common. However, you can make your own wefts from any bulk synthetic hair following this tutorial. Because making wefts is time intensive, I suggest using Microfiber synthetic hair.

Sew in Wefts with Cornrows: First, you need to be able to cornrow; watch this excellent tutorial on how to do this. After laying down a horizontal cornrow, weft hair is sewn onto the cornrow. To see this, watch this tutorial; to see it in more realistic high speed, watch this video. For this, you will need hair on a weft. Human hair is widely available on wefts, whereas synthetic hair is less common. However, you can make your own wefts from any bulk synthetic hair following this tutorial. Because making wefts is time intensive, I suggest using Microfiber synthetic hair.

Shrinkies: Examples here. Small cylindrical tubes lined with glue. Natural hair and extension hair are passed through the tube, then heat is applied to the tube. The tube shrinks while also bonding the glue to the hair. For removal the shrinkie is reheated and pulled away; glue residue is removed with acetone. See this page for several tutorials on shrinkies.

Cold Bonding: The use of unheated glues to attach extension hair to natural hair either strand by strand or weft. Liquid Gold (acrylic based) and Latex glues are two examples of cold bonding glues. These bonds are removed with specific dissolving lotions. See this page for several tutorials on cold bonding.

Fusion Bonding: The use of glue and heat to attach extension hair to natural hair either strand by strand or weft. Most heated glues are keratin based and must be removed with acetone. See this page for several tutorials on fusion bonding.

I also think you should really look at

 Doctored Locks

She has loads of really good video tutorials and PDF's that are easy to follow and also sells everything you will need.