Your Base Bank may be (i) a lump-sum for the season, provided at the start or (ii) a series of weekly bets of a fixed amount. Arrangement (ii) is the most common, usually due to there not being enough money in hand to put together a big base Bank at the outset of the season.
The primary point is that your Base Bank must be considered to be the total amount that you are prepared to stake over the course of the whole season. To consider your Base Bank as being anything other is to delude yourself, especially when you try to derive statistics about your actual betting performance.
Next (and this is a lot easier if your Base Bank is of the weekly contribution type) you must decide how much you are prepared to allocate as your "base stake" each week. When playing roulette at the casino, you can decide in advance how much you are prepared to lose and then, when all your money has gone, you can simply go home and lick your wounds. But if you blow your entire Base Bank on soccer betting by mid-season, you will have to be prepared to play with a smaller bank each week, and at the same time try to scrape the seed money together again to build up a reasonable starting bank for next season.
When considering the level at which you should set your stake over a 40-week season, bear in mind that the average bettor is the typical "man in the street" who bets his full allowance every week, and who generally spends all the winnings and the returned stake, effectively requiring new funds for each week's betting. On that basis, over the course of a 40-week season the layout each week is 2.5% of the Base Bank!
Now, we know that there are Websites out there exhorting you to consider limiting your staking to a maximum of 2% of your Base Bank. Does that make any sense at all? Well, it probably does if you are (i) plucking supposed winners out of the air (thus simply relying on Lady Luck for your selections coming good) and (ii) unable to re-build your Base Bank over the course of the season. Frankly, if you insist on using an inadequate Selection System, then erring on the side of caution is the only way to go from the outset, in which case we suggest you either reduce your weekly staking to 1% of your Base Bank (which will still probably bankrupt you over the course of two seasons) or invest your money in something safer.
Provided that you are employing a worthwhile Selection System (one that gives you an "edge" when betting), then we would advise you to consider setting the initial level for the base stake at up to 5% of your Base Bank. At 5% staking, even if you were to lose everything 19 times running you would still have money left for the 20th outing. But without a good Selection System behind you, we suggest you re-read the previous paragraph!
If you are using a good Selection System, then it is time to consider the various Staking Plan options that are available.