My approach to early stage investing is
a) trying to see good dealflow and
b) picking companies that are likely to get past the Series A-B-C-D bars eventually.
For a) I usually do a lot of outbound to reach companies started by people from networks where I am in (e.g. founders who went to IIT and Stanford where I went to school). I also meet Series A VCs who are interested in my dealflow which I (informally) exchange for filtered dealflow from them.
For b) I use my experience working for experienced investors in the past, whom I have looked at companies together with and learnt from (e.g. Tim Draper at DFJ, a few partners at August Capital and another investor whom I cannot name but is among the top 10 most successful investors in the Bay area). Additionally, I currently advise a $10B AUM family office on their late stage investing and that lets me see late stage dealflow, learnings from which influence my early stage investment selection (I also use my early stage investing experiences in my decision making process for late stage investments). In addition to my evaluation, I also typically check with a few experienced VCs to estimate follow on financing risk.
If you invest in any of my syndicates, I would encourage you to invest an amount you are ok putting at risk preferably based on information about the company (in their deck) and not too much based on whether and how much I am investing.
The investments I try to make are in competitive rounds and so, a quick decision from you will help and in addition, please expect a 90% close rate - that 10% of the time, even after a syndicate successfully closes we may not be able to complete the investment (in which case you get your investment back) - while I can aim for a 100% close rate, the good deals tend to be competitive and my personal preference is to focus on quality than close rate.
I typically try to syndicate all early stage deals I do on Angellist unless there are reasonable circumstances not to. Reasonable circumstances in the past have included the founder not wanting to use an AL syndicate, allocation being below $80K, relationship risk with company's VCs/lawyers due to terms that prevent SPVs etc, deal having a low chance of closing in the needed timeframe (usually 1 week), Angellist investment committee passing on deal (this has been the main reason so far for not syndicating), investment being a secondary and not primary investment etc. I also may invest via one or more parallel investment vehicles (that I also use when the allocation is below 80K).