Je n'ai pas aucune idée cde que jcomment m'habillerai.

"habiller" means "to dress" (something/someone else)
To get dressed is "S'habiller" (reflexive verb), lit. "to dress oneself"
Alternative: "je n'ai aucune idée de ce que je pourrais mettre"

Mon ami veuxt celeélébrer son anniversaire et il n'a pas les d'amis.

Indefinite quantity of something = de (this is a bit the equivalent of "some", but it's much more frequent in French than in English)

Il m'a dis à moit que je pourrais inviterai tous mes amis et ilqu'il me payerait mon loyer, parce que je suis au chômage.

Neutral indirect object pronouns = me, te, lui, nous, vous, leur. "Me" is abbreviated in front of vowels, so => m'
If it was a suggestion he made, it's better to use "pourrait" (could)
Future action (pay your rent) from a past perspective (what he told you) => conditionnel, "payerait"

Je lui dis que je veux essayerai dit que j'essaierais, mais que je ne promettais rien parce que mes amis sont compliqueés.

If you want to emphasize the fact there's no guarantee of result, the most natural way to put it in French would be this one. "Je ne promets rien" is also a pretty common thing to say when you're not sure you can do something for someone
son = his, her, its (masculine) ; sont = are (they)