@Om More Thanks.
1. Try to apply from as many accounts as possible.
2. Try to apply from categories where probability of allotment is higher (generally Retail and BHNI)
3. Sometimes there are IPOs where retail portion is not subscribed fully (e.g. Medanta, Mankind, Vodafone). These are rare but golden chances. Apply fully from Retail category. Just ensure that other categories are oversubscribed in such IPOs.
4. If there are Mainboard as well as SME IPOs at the same time, give more weightage to Mainboard IPO even if GMP is much less there compared to that of SME IPO.
5. Most important - Keep trying.
Best of luck.