This will depend upon your real hair - if you have fine, thin hair then we suggest you use our 120g - 140g clip in packs. If your hair is medium - thick then we recommend that you get between the 160g - 220g clip ins. For those of you who want to have super thick, mermaid hair you should go for the 220g packs providing that your hair is medium - thick. The amount of packs you purchase should also be based on how much volume you are looking for, we suggest starting with 2 packs, unless you have thin hair in which case you might be good with one.