If you have enough funds to be into the top 100 hodlers, than try poolz for getting allocation easily. On the other hand, OP can try gate, mexc exchange as many IDO project also do their fund rising in there and list into those. In both case, you need to have quite huge amount of funds to be in the list. If you're really that much interested into IDOs, than join any VCs where you will be invest with them in those projects for private sale, but you need to keep in mind that there will be lockup period for vesting tokens. As always, DYOR before taking any decision.