I had the experience of helping my brother to sell his house last year.
In my opinion, you can opt to sell your house by yourself if you are:
1. living in the vicinity of the property
2. can afford to spend time showing prospective buyers your unit (for umpteen times, or more)
If you are not, then you may be much better off engaging a real estate agent.
Since I live very near my brother's apartment, and I was on maternity leave at that time, I met the above 2 criteria ;-)
First I took pictures of the apartment unit, including interiors, and posted it on the usual property-for-sale websites. To increase the chances of people hitting my advertisement, I posted on as many relevant websites as I could. Then I waited for calls from prospective buyers to view the apartment.
When a prospect called, we would arrange for a time to view the unit. Usually I would bring a friend or family member along, for safety reasons.
When showing your unit to the prospective buyers, try to offer useful information that is relevant. The availability of schools, kindergartens and daycare facilities, for example, is helpful information to a family with kids. Do not try to oversell and appear desperate, keep your cool and let the discussion take its course. Remember you might go through many viewings before finally encountering a genuine buyer. There are many people who view houses without any real intention to buy, perhaps they are just surveying the area.
When a prospect offer to buy the house, arrange for a time to meet again to sign an agreement to purchase. This agreement can be a simple document signed by both parties, and at this signing the buyer has to pay 2% earnest deposit. In the agreement, it is also stipulated that the buyer must execute the sale & purchase agreement (SPA) within 14 working days (or more depending on the arrangement with the seller), failing which the deposit is forfeited. Give a copy of the agreement to purchase to the buyer. The buyer will then get his lawyer to prepare the SPA and at the same time he would apply for a bank loan.
You should not reserve your unit for the buyer until he has signed the agreement and paid the 2% earnest deposit. If you do, you might miss other prospects wanting to view and buy your unit, should the first buyer breaks his verbal promise.
After the agreement to purchase is signed, do pass your old SPA and a copy of the title to your lawyer, so that he has the details to deal with the buyer's lawyer. Otherwise the SPA will not be completed on time as agreed.
And there, it is done. You have just sold your house! It takes a lot of effort, but it saves you 2% of sale price in agent's commissions.