First rehab:
1) Under estimating the scope of work. Entire rooms needing to be rebuilt from the studs up. All new electrical. All new plumbing. All unexpected.
2) Not having a very clear, defined plan/schedule for rehab. I wasted time by adding renovations as I went.
3) Trying to do it all myself (ok 90% of it) while working a full time job. 90 hour weeks between my job and the house for 6 straight months are not fun.
All these mistakes led to a MUCH longer holding time than was expected. My market seems to be improving, which lessens the effects. If the market was declining, it could have killed my profits.
Should still make a nice profit on this one but it has definitely changed my mindset as to how I will handle deals going forward. The plan for the next deal is to buy it cash to avoid the holding costs/transaction fees and get a better discount on the house. I would also like to hire out 90% of the rehab and only spend my time on the planning/decision making.