I don't play 18-man SNGs, but I can tell you what the strategy is. You need to build a stack early or you'll never win it. The blinds are going to move quick, so there is no time to wait around. See as many cheap flops as you can with speculative
hands (connectors, suited connectors, one-gap suited connectors, etc.) early on and hope you hit at least one and you get paid off. To be honest, these types of SNGs are going to come down to mostly luck (see The Poker Tournament Formula). If you don't see flops, you won't be giving yourself the opportunity to get lucky. If you do happen to build a stack early, don't go into survival mode. You have to constantly be aggressive and keep building your stack if you want any chance of winning.