While starting out, it is difficult to stick with one purchase, as most often than not, there are other companies that seem to be favourable after you’ve made a certain purchase. To overcome this, you need to have enough cash in the account, not because you can make that other purchase but so that you know if it is really lucrative (after doing the research), you have the capability to make the buy rather wait another month or so, to contribute the amounts in order to make the purchase.
At times, when you find yourself going to the same company, you should really make that buy. Chances are it will not stay at those price levels forever, and you might find yourself thumb sucking waiting for a better opportunity only to find out you’ve forgone that better opportunity.
Another interesting advice I picked up while visiting the personal finance blogs and reading many books was to trust your instinct. It is tough to zero in on an investment but tougher to persist with it. Most often, I found myself adding to my stock position when there is a market correction. Now, this is all after putting in my time to research about a given security.