Wow Thomas. With that 4 part question be prepared for either VERY long responses or no responses. I will try to get things going for you.
1) Figuring out my first deal is a little difficult. I had been studying RE like you and I had a local investor guiding me. After reading, looking, asking and attending local landlord club he told me to either invest or stop bothering him, (do or don't do but make a decision and go with it). I got with a realtor and found a really beat up 3/1 SFH on the MLS for about $10k (1999). I put an offer in and we had it under contract soon after. While waiting to close on this REO property, I was driving for dollars and found a FSBO sign in the window of a little 2/1 SFH. I called and we struck a deal for $15k (it was basically rent ready). We closed on that property before we closed on the bank owned beat up. You decide which was the first deal. I paid for them using savings and a HELOC on my principal home. I guess that answers how soon I moved on to the next deal also. When my mentor told me to act I went into full beast mode.
2) As for the Best deal, that is hard to decide. I do not buy unless I believe it to be a great deal at time of purchase. The best deals have not revealed themselves until way after the fact. One in particular goes like this. A friend bought a package of 5 houses. There was 1 that he did not want and asked me what I would give him for it. I told him I did not want it but he persisted. I eventually bought it for $7k. No furnace, no kitchen, no bathroom, and about half the windows missing. I sold it on contract for $1k down and $200/mo for 5 years. After about 6 months the buyer lost his job and gave back to me. It now had a furnace, a rough kitchen and a partial bathroom along with all windows. I then sold it for $2k down and $250/mo for 5 years. Once again, after about 3 years the buyer called and said his son moved out and he did not want the house. He gave it back to me. It now had siding on 2 sides and the rest in the garage, a better bathroom and a full albeit dated kitchen and the windows now actually kept the weather out. Before I could "sell" it again, I got a letter from the City saying they wanted it for a road project and they would give me $20k and I could keep the furnace. Just goes to show that sometimes the best deals are not revealed until way after the fact.
3) Worst deal is one that a friend warned me about but I "knew better". $18k for a 2/1 recently "updated" and rent ready. It was right behind a local housing "project" for low income people. The first tenant rebuilt a motorcycle int he Living room, destroying the carpet, had to be evicted and left me about $3k in damages. While vacant an enterprising neighbor decided to recycle the siding. The neighbors in the projects kept tossing their trash into my yard and after about 2 years I sold it for $10k. Happy to be done with that nightmare. I learned never to buy in an area like that again.
4) My strategy is to buy / fix / hold. I started in 1999 and I currently have 66 SFH that I rent, 11 of which I own outright. This is my sole source of income to support my family and I would not change it for anything. I only buy if I can borrow the total purchase and rehab costs once the property is renovated. I work with a local bank that will loan me up to 70% of appraised value (ARV). As long as that cover my entire investment and it generates close to $200/mo (cashflow AND debt paydown) from day 1 I will make it happen.
Good luck and as my mentor said. Buy something or stop pretending. The only way to get into this business is to take the first step.